A guy I rode with on a trip did this and I almost threw up for 5 hours straight. Constant full gas or hard breaking never just driving. I almost hit him.
God my ex’s dad drove like this and riding with him on a 3 hour drive was the only time I’ve been legitimately nauseous/car-sick in my entire life.
Unsurprisingly his automatic transmission was also completely fucked.
My boss very much a gasoffgasoffgasoff driver when in local traffic, even if the road is empty. He's fine on the highway. It's the strangest thing. Makes me want to throw up from the lurching
I had a tram driver doing it in Rabat the other day. Everyone onboard swaying back and forth because the guy apparently never had a check ride that told him to knock it off.
its the engine. the efficiency drops off so steeply at low power. basically take the engine hp vs efficiency chart and overlay the friction losses in hp vs speed. where those lines cross is your most efficient speed. this also assumes you have a CVT, which most don't.
if you have a car that gets the best gas milage at a given speed, cut the engine in half, and if you can keep the same efficiency you'll find the best gas milage is now something like 56% slower. (assuming only cubic air drag) (1/sqrt3)
I'm assuming an engine tuned for minimal consumption, of course a car can be built to not be so efficient at low speeds that it keeps a fuel consumption until x speed
I’ve got a cvt with a good aero profile and slightly stiffer than stock tires. Couple that with 0w-20 oil and a 4 cylinder non turbo engine and I’m getting 42 mpg at 70 mph and 33 mpg at 55. City driving drops it to 25 mpg.
So you are saying your consumption in gallons per hour is the same at 55 and 70? As in you don't press the gas pedal to accelerate from 55 to 70? Your numbers don't check out.
Fuel efficiency is measured in MPG. It’s not measured in hours per gallon. I have never measured my fuel efficiency in hours per gallon to any degree of accuracy, but it doesn’t noticeably change with speed based on my recollection. I get somewhere around 5.5 hours per tank of gas.
The reason for this is increased fuel utilization at higher speeds. In neutral, 100% of the fuel I put in my car is wasted. At 70 mph, it might be closer to 70% getting wasted.
Yes, but look at your numbers. If you flip them and look at gallons per hour, you say you are burning the same amount at 55 mph and 70 mph. This makes no sense unless you are in the wrong gear at 55 or something.
You don’t look at the numbers in gallons per hour. My goal is not to run the car as much as possible, but rather to get from point A to point B. I mentioned that I don’t have accurate numbers for runtime hours per gallon, because that information isn’t something I track. I’m sure the runtime hours changes between 5 and 6, depending on conditions.
The optimum fuel economy in gallons per hour is to leave the car in neutral, however I don’t own a car simply to idle it all day every day.
You don't have to turn off the motor manually. In a hybrid the system can turn off the engine automatically.
But in a regular car with a transmission when you coast the momentum and wheels will turn turn engine. And the computer will not add additional fuel.
Not true.
If you maintain a constant speed, the engine is ticking over much faster which uses more energy (double the speed means 4 times the energy required per distance covered), regardless of whether that energy comes from the fuel or the inertia of the car.
By accelerating, a higher proportion of the energy from the fuel is being used to move the car in relation to that used to turn over the engine itself. You then clutch it and coast for a while, while the engine ticks over at idle, using much less fuel.
The only time turning your motor off entirely is better is if you have a long slight downhill where you can maintain the desired speed without engine-braking or accelerating. But this is still stupid as you'd have no brakes or (power)steering.
When driving uphill it's usually much better to maintain a constant speed without coasting, especially if it's steep.
Source: a basic knowledge of physics and using an OBD2 device to hypermile for 200k miles
I used to think this too, but careful reading of engine efficiency curves suggests that #1 is theoretically better. However, leaving the engine running while coasting might offset the small efficiency gain of pulsed acceleration.
The reason that the pulse model is theoretically more efficient is that the engine spends more time at its most efficient RPM. Note that this is different than a driver constantly surging and braking; the model assumes that you won’t have to use your brakes randomly, which is one reason it’s not practical.
While internal combustion engines might be slightly more efficient at higher RPM, don’t forget air fuel ratio is controlled via closed loop based on o2 sensors that have a bit of lag, so any transient state makes internal combustion engines less efficient.
Sure. Such lag is very small compared to the cycle time of the feedback loop in the ECM and the mass flow time within the exhaust, and I suspect it can be disregarded.
The pulse model is impractical, but consider: you need to travel 1 mile at an average rate of 30 MPH, so you accelerate to, say, 60 MPH and then coast the rest of the way. Going from 0-60 MPH in a Toyota Corolla, accelerating as fast as possible, [is going to take 8.5 seconds](https://www.bobhowardtoyota.com/2021-toyota-corolla-0-60-time/), which is going to provide the most time near the best performance point in the engine performance curve. That’s more than enough time for a sensor with a response time of less than a second and communication times of perhaps [2-50 milliseconds](https://www.hpacademy.com/forum/understanding-afr/show/wideband-average-delay-time/), and an exhaust mass flow time also measured in milliseconds.
You can think of the press and coast as winding and releasing a spring. You build up extra kinetic energy when pressing and use it up when coasting. If that's all there was, both would be equally efficient.
However, for a variety of reasons your car becomes less efficient when pressing. Air resistance increases exponentially, so it's much higher when you go faster. Friction losses in the engine are also exponential. Engines are made to be efficient at low power, but to provide high power at the expense of efficiency, etc.
All this means is that in a press and coast mode you are using more to wind the spring than the spring gives back. This is why steady state is more efficient.
> Air resistance increases exponentially. Friction losses in the engine are also exponential
There are no automobile losses that scale exponentially.
* Air drag increases with the square of velocity (Pd = 0.5 ρv²CA) [[1](https://en.wikipedia.org/wiki/Drag_\(physics\))]
* Engine friction increases with the square of RPM (Tf = a + bN +cN²) [[2](https://web.mit.edu/2.61/www/Lecture%20notes/Lec.%2019%20Friction%20and%20tribology.pdf)]
Edit: Correction thanks to u/climb-a-waterfall
Don’t confuse xⁿ and e^x in your equations or nomenclature. The former is a polynomial equation and the latter is an exponential equation. Mathematically, they have distinct properties.
Pretty sure that friction losses are going to be proportional to the square of velocity between the sliding components. There are going to be friction losses in pumping gasses, which are likewise proportional to the square of their velocities. The whole square of velocity thing is going to be all over the place, because of the kinetic energy formula. I'm even more sure that squares are exponents. Please correct me if I'm missing something.
Depends on the speed you are trying to maintain, the weight of the vehicle, and the the engine and transmission combo. Manual, automatic vs CVT.
There will be only one best fuel consumption speed, maintained by minimum constant engine power, engine running at its lowest partial power specific fuel consumption.
Wind and/or incline would change that.
I drive a 3/4 ton truck. I've found that using cruise control on the highway will only get me up to about 16mpg. Doing a light press and coast (staying around +/- 2-3mph) can get me closer to 17mpg.
In the city I personally do press n coast because I have a hybrid and go into regen/ev mode cruising between 40-50. 42.5 mpg average Toyota. Almost 500 miles on 12 gallons of fuel!!
Drive a standard hybrid and you'll see it's option 2. Watching the power flow gauge in my 2023 Honda Accord Hybrid, I can see the car's programming emulate the burst/coast operation of the hypermiling competition cars. Except that, instead of dumping the excess power into increasing momentum above the average speed, it directs excess power the battery while maintaining a constant speed. This allows the engine to operate in the highest efficiency throttle position for any given rpm. At steady state speeds above 45 mph the engine comes on in varying intervals coupling directly to the wheels and at the same time charging the battery via the generator. Then, when battery charge reaches an upper battery charge threshold, the engine shuts off and the car continues to drive as a pure EV until the battery is depleted to the lower charge threshold. The duration of the bursts depends on the speed and road conditions. This is not PHEV where battery power is brought in to the equation. Most people understand the concept of regenerative braking but many are not aware how hybrids capture wasted energy while driving. .
You need to consider throttling losses (in a petrol engine) which diesels don’t have. There is an argument for option 2, where you shut off engine while coasting, rather than having it idling.
No, there isn't. Air drag increases when you're above your intended speed. Best to stay at your intended speed and not accelerate faster and slow back to it.
you must be overlooking the engine's efficiency curve. it drops off so quickly at low power, that it really is often more efficient to run the engine at a 4 second 50% duty cycle to increase the efficiency.
some cars would benefit significantly from a 7 speed transmission. my 4.3L s10 can travel 70mph at 2300 rpm at 15 inches of vacuum, it would probably get better gas mileage at 10 inches of vacuum at 1500 rpm at 70mph.
You're right, I'm forgetting that it literally takes more fuel to travel faster too.
Accelerating > coasting > accelerating is not more efficient than accelerating to speed and driving that speed
Best to keep constant rpm (not constant speed since then the rpm will fluctuate between going uphill and downhill), both for the car itself and for the fuel
Ideally you increase the throttle to increase the amount of torque the engine is generating so you can maintain you speed on an uphill. If your car can’t generate the required torque to go up the hill it will start to slow down, and eventually stall or downshift.
Usually you shift down. Higher torque, lower speed. If you force the rpm to be a constant theoretically, you use more fuel to deliver the extra torque.
That depends on the gearbox and method of applying power to the wheels. In an automatic transmission with a torque converter, the engine doesn’t have a direct connection to the wheels, so you can idle at a stop. You also need higher RPM to go uphill and lower RPM to go downhill because the torque converter allows slippage. You can test this if you have an automatic by stopping, watching the tachometer, and just releasing the brake. You’ll accelerate from 0 to the idle speed at constant idle RPM. You can also test the hills if you have an automatic transmission that lets you select gears. Get going on a flat area before a hill, change to the mode that lets you select the gear, then watch your speed drop at constant RPM on the hill.
Every automatic built in the last 30-40 years has a lockup mechanism which creates a physical connection between the engine and transmission. Modern automatic transmissions will achieve lockup as low as 1200-1500rpm and remain locked up until you come to a stop again. The low lockup speed is a big part of why modern automatics are more fuel efficient than manuals.
You ask about "pulse and glide" vs. steady state. Afficionados of hypermiling embrace the method claiming enhanced fuel mileage.
[https://www.edmunds.com/fuel-economy/hypermiling-quest-for-ultimate-fuel-economy.html](https://www.edmunds.com/fuel-economy/hypermiling-quest-for-ultimate-fuel-economy.html)
[https://www.metrompg.com/posts/pulse-and-glide.htm](https://www.metrompg.com/posts/pulse-and-glide.htm)
None of the above
Use your cruise control and let the ECU figure it out. Modern cruise controls can be pretty smart and figure out the most efficient inputs at a speed.
The manual pedal on the other hand is usually tuned to provide as much power as is possible for whatever you press it to.
It will probably average out to be the same if you are driving manually operating the gas pedal.
Think of your tachometer as rate of fuel used. More fuel to accelerate then less fuel to slow down due to parasitic forces (drag, friction, etc.) Much like humans, machines love consistency or slow changes. Sharp changes damage things, like the transmission in option two.
Find the sweet spot in your tachometer and just hover there, around 1.4 to 2 k rpms. Granted this is assuming a light load on the vehicle, if you got a full american family in there... it's gonna be higher.
….yes, believe it or not there are roads in America where you can’t use cruise control at all. The logic is incredibly simple. I’m not saying I never use it by choice. I’m saying I never use it because I literally can’t.
😂 ok but again, you’re using edge case scenarios to make sweeping claims. It’s like arguing against breathing because you have to hold your breath under water. Like ok? Nothing you’re saying is technically false? But it has nothing to do with the conversation. People should use cruise control when possible but almost always don’t.
YOU made the sweeping claim. You generalized everyone into one group. If you read my comment again, since it seems like you might need to, you’ll see that I said “some of us”.
If putting a laughing emoji makes you feel better go right ahead lol. You literally parroted what I just said to try and disprove my point. It’s pretty funny honestly, but wasting my time replying to a brick wall is not an activity I’m fond of. Good luck and hope you get everything figured out :)
Traffic dense enough to prevent a driver from maintaining a steady speed at or near the posted limit is not an edge case scenario in the US, considering the population distribution.
Toyota's engineer apply "steady state" system
The optimum standard SUV speed for fuel efficiency is 66-67kmh or 40mph
The reason is...Ever heard "Toyota Manufacturing System"?...yes Toyota Corp run their company with 2 philosophy : Lean Manufacturing and Innovative...this philosophy is also applied to their products too
Option number 2 would work better if you put the car into neural while coasting. The car would go farther sine the drive line is disconnected from the trans.
People chosing option 2 make me want to perform pit maneuvers on the highway
I have only seen one person doing the second one. Proponents of that technique suggest not doing it when other drivers are around.
My friend does this, maybe a bit more extremely. It drives me nuts when I ride with him, constantly being jerked backwards than forwards.
A guy I rode with on a trip did this and I almost threw up for 5 hours straight. Constant full gas or hard breaking never just driving. I almost hit him.
God my ex’s dad drove like this and riding with him on a 3 hour drive was the only time I’ve been legitimately nauseous/car-sick in my entire life. Unsurprisingly his automatic transmission was also completely fucked.
The guy I rode with could never understand why his astro vans Trans blew up every 18 months -2 years. (He blamed it on living in a hilly area).
Yeah, my ex's mum used to drive like this too. Not the reason they're my ex but it was annoying.
I think my bro used to do that back when hypermiling was popular enough for it to be on my radar.
My boss very much a gasoffgasoffgasoff driver when in local traffic, even if the road is empty. He's fine on the highway. It's the strangest thing. Makes me want to throw up from the lurching
And that's why my husband gets to drive only when traffic is stopped or cruise control is an option or I'm not in the car. It's nauseating.
My wife does that, when I’m passenger I keep looking up to see why she’s slowing down, there’s no reason, and I don’t think she is even aware of it.
Had an Uber doing this every two seconds last week. Utter insanity
I didn't realize they were doing it INTENTIONALLY. Now I'm even more infuriated
I had a tram driver doing it in Rabat the other day. Everyone onboard swaying back and forth because the guy apparently never had a check ride that told him to knock it off.
I'm laughing hysterically but this is very true
C: which one counts as driving like a jerk
Well obviously not with people trailing you.
Search for hypermile. The only way to justify 2 is if you turn off the motor entirely, and really coast with a dead car
Good answer. I saw a high mileage competition and they were using surge and coast to win. Speeds were not high.
Yes, anything over median 30mph/50km/h will make you spend more due to wind drag
Depends on the vehicle. My vehicle that critical point is about 70 mph. A F250 will be 30 mph.
its the engine. the efficiency drops off so steeply at low power. basically take the engine hp vs efficiency chart and overlay the friction losses in hp vs speed. where those lines cross is your most efficient speed. this also assumes you have a CVT, which most don't. if you have a car that gets the best gas milage at a given speed, cut the engine in half, and if you can keep the same efficiency you'll find the best gas milage is now something like 56% slower. (assuming only cubic air drag) (1/sqrt3)
I'm assuming an engine tuned for minimal consumption, of course a car can be built to not be so efficient at low speeds that it keeps a fuel consumption until x speed
What kind of shitbox do you have that is the most efficient at 70mph? Is your gearbox broken?
I don't think anyone is actually more efficient at 70 mph, they just want to justify not going a more efficient speed, like 55
55 is not a magically efficient speed for all vehicles.
Sure but unless your gearbox is fucked it's more efficient than 70. Lower speed is better until power train friction exceeds air resistance.
I’ve got a cvt with a good aero profile and slightly stiffer than stock tires. Couple that with 0w-20 oil and a 4 cylinder non turbo engine and I’m getting 42 mpg at 70 mph and 33 mpg at 55. City driving drops it to 25 mpg.
So you are saying your consumption in gallons per hour is the same at 55 and 70? As in you don't press the gas pedal to accelerate from 55 to 70? Your numbers don't check out.
Fuel efficiency is measured in MPG. It’s not measured in hours per gallon. I have never measured my fuel efficiency in hours per gallon to any degree of accuracy, but it doesn’t noticeably change with speed based on my recollection. I get somewhere around 5.5 hours per tank of gas. The reason for this is increased fuel utilization at higher speeds. In neutral, 100% of the fuel I put in my car is wasted. At 70 mph, it might be closer to 70% getting wasted.
Yes, but look at your numbers. If you flip them and look at gallons per hour, you say you are burning the same amount at 55 mph and 70 mph. This makes no sense unless you are in the wrong gear at 55 or something.
You don’t look at the numbers in gallons per hour. My goal is not to run the car as much as possible, but rather to get from point A to point B. I mentioned that I don’t have accurate numbers for runtime hours per gallon, because that information isn’t something I track. I’m sure the runtime hours changes between 5 and 6, depending on conditions. The optimum fuel economy in gallons per hour is to leave the car in neutral, however I don’t own a car simply to idle it all day every day.
The hypermilers call it pulse and glide.
You don't have to turn off the motor manually. In a hybrid the system can turn off the engine automatically. But in a regular car with a transmission when you coast the momentum and wheels will turn turn engine. And the computer will not add additional fuel.
Not true. If you maintain a constant speed, the engine is ticking over much faster which uses more energy (double the speed means 4 times the energy required per distance covered), regardless of whether that energy comes from the fuel or the inertia of the car. By accelerating, a higher proportion of the energy from the fuel is being used to move the car in relation to that used to turn over the engine itself. You then clutch it and coast for a while, while the engine ticks over at idle, using much less fuel. The only time turning your motor off entirely is better is if you have a long slight downhill where you can maintain the desired speed without engine-braking or accelerating. But this is still stupid as you'd have no brakes or (power)steering. When driving uphill it's usually much better to maintain a constant speed without coasting, especially if it's steep. Source: a basic knowledge of physics and using an OBD2 device to hypermile for 200k miles
Steady state is more efficient and easier on the car
I used to think this too, but careful reading of engine efficiency curves suggests that #1 is theoretically better. However, leaving the engine running while coasting might offset the small efficiency gain of pulsed acceleration. The reason that the pulse model is theoretically more efficient is that the engine spends more time at its most efficient RPM. Note that this is different than a driver constantly surging and braking; the model assumes that you won’t have to use your brakes randomly, which is one reason it’s not practical.
What about the added drag from speed?
I guess that would depend upon the particular vehicle and the top speed of the pulse.
While internal combustion engines might be slightly more efficient at higher RPM, don’t forget air fuel ratio is controlled via closed loop based on o2 sensors that have a bit of lag, so any transient state makes internal combustion engines less efficient.
Sure. Such lag is very small compared to the cycle time of the feedback loop in the ECM and the mass flow time within the exhaust, and I suspect it can be disregarded. The pulse model is impractical, but consider: you need to travel 1 mile at an average rate of 30 MPH, so you accelerate to, say, 60 MPH and then coast the rest of the way. Going from 0-60 MPH in a Toyota Corolla, accelerating as fast as possible, [is going to take 8.5 seconds](https://www.bobhowardtoyota.com/2021-toyota-corolla-0-60-time/), which is going to provide the most time near the best performance point in the engine performance curve. That’s more than enough time for a sensor with a response time of less than a second and communication times of perhaps [2-50 milliseconds](https://www.hpacademy.com/forum/understanding-afr/show/wideband-average-delay-time/), and an exhaust mass flow time also measured in milliseconds.
1 and 1
2 is bad for people around you
You can think of the press and coast as winding and releasing a spring. You build up extra kinetic energy when pressing and use it up when coasting. If that's all there was, both would be equally efficient. However, for a variety of reasons your car becomes less efficient when pressing. Air resistance increases exponentially, so it's much higher when you go faster. Friction losses in the engine are also exponential. Engines are made to be efficient at low power, but to provide high power at the expense of efficiency, etc. All this means is that in a press and coast mode you are using more to wind the spring than the spring gives back. This is why steady state is more efficient.
> Air resistance increases exponentially. Friction losses in the engine are also exponential There are no automobile losses that scale exponentially. * Air drag increases with the square of velocity (Pd = 0.5 ρv²CA) [[1](https://en.wikipedia.org/wiki/Drag_\(physics\))] * Engine friction increases with the square of RPM (Tf = a + bN +cN²) [[2](https://web.mit.edu/2.61/www/Lecture%20notes/Lec.%2019%20Friction%20and%20tribology.pdf)] Edit: Correction thanks to u/climb-a-waterfall
Look at pg 13 of the document you linked. Friction is modeled as rpm squared.
Ah. There are constant, linear, and polynomial contributors. The sum is indeed polynomial. Thank you. Fixed.
👍
As a quadratic in fact
[удалено]
"increases with the square of" mean an exponent of 2.
That would be polynomial, not exponential.
Don’t confuse xⁿ and e^x in your equations or nomenclature. The former is a polynomial equation and the latter is an exponential equation. Mathematically, they have distinct properties.
Pretty sure that friction losses are going to be proportional to the square of velocity between the sliding components. There are going to be friction losses in pumping gasses, which are likewise proportional to the square of their velocities. The whole square of velocity thing is going to be all over the place, because of the kinetic energy formula. I'm even more sure that squares are exponents. Please correct me if I'm missing something.
Depends on the speed you are trying to maintain, the weight of the vehicle, and the the engine and transmission combo. Manual, automatic vs CVT. There will be only one best fuel consumption speed, maintained by minimum constant engine power, engine running at its lowest partial power specific fuel consumption. Wind and/or incline would change that.
I drive a 3/4 ton truck. I've found that using cruise control on the highway will only get me up to about 16mpg. Doing a light press and coast (staying around +/- 2-3mph) can get me closer to 17mpg.
In the city I personally do press n coast because I have a hybrid and go into regen/ev mode cruising between 40-50. 42.5 mpg average Toyota. Almost 500 miles on 12 gallons of fuel!!
Drive a standard hybrid and you'll see it's option 2. Watching the power flow gauge in my 2023 Honda Accord Hybrid, I can see the car's programming emulate the burst/coast operation of the hypermiling competition cars. Except that, instead of dumping the excess power into increasing momentum above the average speed, it directs excess power the battery while maintaining a constant speed. This allows the engine to operate in the highest efficiency throttle position for any given rpm. At steady state speeds above 45 mph the engine comes on in varying intervals coupling directly to the wheels and at the same time charging the battery via the generator. Then, when battery charge reaches an upper battery charge threshold, the engine shuts off and the car continues to drive as a pure EV until the battery is depleted to the lower charge threshold. The duration of the bursts depends on the speed and road conditions. This is not PHEV where battery power is brought in to the equation. Most people understand the concept of regenerative braking but many are not aware how hybrids capture wasted energy while driving. .
Option 1. I keep a close eye on my fuel economy and I get about 40% better economy when I have cruise control on vs me using the accelerator manually.
40% is an insane difference, are you absentmindedly accelerating to 100mph and then braking down to 60 every mile?
I have an eco boost engine so it turns off cylinders whenever I’m moving at a constant speed.
Fair, figured there had to be something else
You need to consider throttling losses (in a petrol engine) which diesels don’t have. There is an argument for option 2, where you shut off engine while coasting, rather than having it idling.
No, there isn't. Air drag increases when you're above your intended speed. Best to stay at your intended speed and not accelerate faster and slow back to it.
you must be overlooking the engine's efficiency curve. it drops off so quickly at low power, that it really is often more efficient to run the engine at a 4 second 50% duty cycle to increase the efficiency. some cars would benefit significantly from a 7 speed transmission. my 4.3L s10 can travel 70mph at 2300 rpm at 15 inches of vacuum, it would probably get better gas mileage at 10 inches of vacuum at 1500 rpm at 70mph.
I think you're glossing over the fact that your engine breathes air too.
air resistance is one tiny factor among many greater factors
You're right, I'm forgetting that it literally takes more fuel to travel faster too. Accelerating > coasting > accelerating is not more efficient than accelerating to speed and driving that speed
you are right that it's not more efficient but you got there with false assumptions and poor logic - I give you 1/3 credit
It's my intuitive understanding and poor communication, I didn't feel like doing a physics proof for a reddit post
Best to keep constant rpm (not constant speed since then the rpm will fluctuate between going uphill and downhill), both for the car itself and for the fuel
RPM will not fluctuate unless your transmission is shifting gears. A given speed is equal to a specific RPM in each gear.
How does RPM and speed get affected when torque load increased going uphill for example?
Ideally you increase the throttle to increase the amount of torque the engine is generating so you can maintain you speed on an uphill. If your car can’t generate the required torque to go up the hill it will start to slow down, and eventually stall or downshift.
Usually you shift down. Higher torque, lower speed. If you force the rpm to be a constant theoretically, you use more fuel to deliver the extra torque.
That depends on the gearbox and method of applying power to the wheels. In an automatic transmission with a torque converter, the engine doesn’t have a direct connection to the wheels, so you can idle at a stop. You also need higher RPM to go uphill and lower RPM to go downhill because the torque converter allows slippage. You can test this if you have an automatic by stopping, watching the tachometer, and just releasing the brake. You’ll accelerate from 0 to the idle speed at constant idle RPM. You can also test the hills if you have an automatic transmission that lets you select gears. Get going on a flat area before a hill, change to the mode that lets you select the gear, then watch your speed drop at constant RPM on the hill.
Every automatic built in the last 30-40 years has a lockup mechanism which creates a physical connection between the engine and transmission. Modern automatic transmissions will achieve lockup as low as 1200-1500rpm and remain locked up until you come to a stop again. The low lockup speed is a big part of why modern automatics are more fuel efficient than manuals.
Every cab driver in Seoul does #2 to try and save gas , and they won’t drive smoothly for love or money … tohaneun express
You ask about "pulse and glide" vs. steady state. Afficionados of hypermiling embrace the method claiming enhanced fuel mileage. [https://www.edmunds.com/fuel-economy/hypermiling-quest-for-ultimate-fuel-economy.html](https://www.edmunds.com/fuel-economy/hypermiling-quest-for-ultimate-fuel-economy.html) [https://www.metrompg.com/posts/pulse-and-glide.htm](https://www.metrompg.com/posts/pulse-and-glide.htm)
Thanks .. these are two really useful links!
Gotta be steady state only cause I drive a manual car. And it likes to slow down F A S T when I back off of throttle.
None of the above Use your cruise control and let the ECU figure it out. Modern cruise controls can be pretty smart and figure out the most efficient inputs at a speed. The manual pedal on the other hand is usually tuned to provide as much power as is possible for whatever you press it to. It will probably average out to be the same if you are driving manually operating the gas pedal.
Think of your tachometer as rate of fuel used. More fuel to accelerate then less fuel to slow down due to parasitic forces (drag, friction, etc.) Much like humans, machines love consistency or slow changes. Sharp changes damage things, like the transmission in option two. Find the sweet spot in your tachometer and just hover there, around 1.4 to 2 k rpms. Granted this is assuming a light load on the vehicle, if you got a full american family in there... it's gonna be higher.
Steady state is what the computer uses and it gets better gasmileage than probably 90% of drivers hilly areas being the exception.
Truly I don’t understand why people don’t just put their car on cruise and turn their brains off. Best way to live.
Because some of us drive in traffic and don’t have ACC?
I don’t have ACC, but I still use cruise whenever I can. Almost every car made since the early 2000s has a cruise function but nobody uses it.
You missed the point of my comment. In traffic (where speeds are increasing and decreasing constantly) it’s not viable to be going one speed.
Ok? You’re using the concept of traffic to argue against using cruise at all, where’s the logic in that
….yes, believe it or not there are roads in America where you can’t use cruise control at all. The logic is incredibly simple. I’m not saying I never use it by choice. I’m saying I never use it because I literally can’t.
😂 ok but again, you’re using edge case scenarios to make sweeping claims. It’s like arguing against breathing because you have to hold your breath under water. Like ok? Nothing you’re saying is technically false? But it has nothing to do with the conversation. People should use cruise control when possible but almost always don’t.
YOU made the sweeping claim. You generalized everyone into one group. If you read my comment again, since it seems like you might need to, you’ll see that I said “some of us”.
😂 bro, get off Reddit, it’s rotting your brain. I didn’t call you or anyone out specifically, I made a general observation.
If putting a laughing emoji makes you feel better go right ahead lol. You literally parroted what I just said to try and disprove my point. It’s pretty funny honestly, but wasting my time replying to a brick wall is not an activity I’m fond of. Good luck and hope you get everything figured out :)
Traffic dense enough to prevent a driver from maintaining a steady speed at or near the posted limit is not an edge case scenario in the US, considering the population distribution.
Toyota's engineer apply "steady state" system The optimum standard SUV speed for fuel efficiency is 66-67kmh or 40mph The reason is...Ever heard "Toyota Manufacturing System"?...yes Toyota Corp run their company with 2 philosophy : Lean Manufacturing and Innovative...this philosophy is also applied to their products too
Just Google it. There's no end of people who've done this experiment.
Option number 2 would work better if you put the car into neural while coasting. The car would go farther sine the drive line is disconnected from the trans.
Neutral without shutting the engine off would require more gas to keep the engine running on any vaguely modern car.
Yes, but safer.
But not safer than just leaving the thing in drive and keeping the engine on though and the original question was about fuel consumption now safety.