OMG Hypermilling rocks

[Engineer]

Originally posted by: Queasy
Hypermiling website

>> The first step toward saving gas and increasing mpg: Always know your gas mileage after each visit to the gas pump.

>> The second step: do you drive agressively but not know it?

>> The third step: How long are you sitting still at red lights? Video

>> The fourth step: Keeping yourself moving in traffic congestion

>> The fifth step: Slowly accelerate after stops

>> The sixth step: Your cruise control saves gas (but not by using it they way you might think)

I've been, without knowing, hypermiling for years. I read a book years ago that described the above buy didn't call it hypermiling. No wonder that I can get 29 mpg in the city and 36 on the highway in our 07 Cobalt and the wife gets 23 mpg in the city and about 30 on the highway!

 

[thomsbrain]

The air conditioner in my Honda Accord uses 1.2 HP according to my Scangauge. Idle is ~6.8 HP with it off, and ~8.0 HP with it on. It takes roughly 25 HP to cruise at 60 MPH on level ground, which means the air conditioner increases the engine load by roughly 5%. Personally I'm willing to live with that if it means I get to be comfortable.

Originally posted by: Connoisseur
Yeah i believe hypermiling involves several, more "extreme", methods to make your car sip fuel. Some examples:
1) Shifting to neutral during downhills to minimize rpms
2) Tailgating trucks to get the drafting effect (although this is a bit extreme)
3) Turning the engine off at long stop lights
4) Accelerating slowly

Those suggestions are all counterproductive.

1. Shifting to neutral forces the engine to use gas to idle. Leaving the car in gear while coasting engages complete fuel cutoff until the engine RPM reaches idle speed again, which means you use zero fuel instead of idle fuel. It's the difference between ~80 MPG while coasting and infinity MPG while coasting. I've verified this with my Scangauge, and anyone can learn to discern the fuel cutoff and cutin with enough practice and sensitivity to their car. LEAVE THE CAR IN GEAR.

2. Yes, drafting can increase mileage a bit, but I've found that because you can't see the road ahead and the truck likely has zero interest in hypermiling, they will hit the brakes in situations where they should have coasted, or in reaction to things you couldn't see. The result is you end up hitting your brakes, too, instead of just coasting like you would have if you could have seen the road. So it's a wash, and it's not really safe anyway. Don't put yourself in situations where other drivers make your choices for you, because they don't care about mileage.

3. Turning off the engine at stoplights just isn't safe (unless you have a hybrid in auto-start mode).

4. Engines achieve maximum efficiency at full throttle. Cars achieve maximum efficiency in the highest gear at the lowest RPM without lugging. So as any hypermiler will tell you, you get the best overall mileage by gunning the trhottle off the line and short-shifting into the higher gears as soon as possible. The idea is to maximize the distance you travel in the top applicable gear for the speed limit. So accelerating like a Grandma will actually return worse mileage. And the suggestions I've seen to let auto-transmission cars "creep" a bit before hitting the gas doesn't hold up well with the data I've seen on my Scangauge. When you creep, you slowly ramp to maybe ~3 MPG. If you hit the gas, it will be showing ~6MPG right off the bat. Again, you need to minimize the time you're not in high gear, and creeping wastes time and distance. The only exception is if you stop a bit back from the car in front and anticipate the green light a bit, in which case you're getting a little movement out of what otherwise would have been a 0 MPG idle.

 

[Capt Caveman]

Originally posted by: thomsbrain
The air conditioner in my Honda Accord uses 1.2 HP according to my Scangauge. Idle is ~6.8 HP with it off, and ~8.0 HP with it on. It takes roughly 25 HP to cruise at 60 MPH on level ground, which means the air conditioner increases the engine load by roughly 5%. Personally I'm willing to live with that if it means I get to be comfortable.

Originally posted by: Connoisseur
Yeah i believe hypermiling involves several, more "extreme", methods to make your car sip fuel. Some examples:
1) Shifting to neutral during downhills to minimize rpms
2) Tailgating trucks to get the drafting effect (although this is a bit extreme)
3) Turning the engine off at long stop lights
4) Accelerating slowly

Those suggestions are all counterproductive.

1. Shifting to neutral forces the engine to use gas to idle. Leaving the car in gear while coasting engages complete fuel cutoff until the engine RPM reaches idle speed again, which means you use zero fuel instead of idle fuel. It's the difference between ~80 MPG while coasting and infinity MPG while coasting. I've verified this with my Scangauge, and anyone can learn to discern the fuel cutoff and cutin with enough practice and sensitivity to their car. LEAVE THE CAR IN GEAR.

<snip>

Infinity MPG? In gear, the engine sure is running and burning fuel. It also is running at a higher rpm than if the car was put into neutral(idle).

 

[overst33r]

Originally posted by: Capt Caveman

Originally posted by: thomsbrain
The air conditioner in my Honda Accord uses 1.2 HP according to my Scangauge. Idle is ~6.8 HP with it off, and ~8.0 HP with it on. It takes roughly 25 HP to cruise at 60 MPH on level ground, which means the air conditioner increases the engine load by roughly 5%. Personally I'm willing to live with that if it means I get to be comfortable.

Originally posted by: Connoisseur
Yeah i believe hypermiling involves several, more "extreme", methods to make your car sip fuel. Some examples:
1) Shifting to neutral during downhills to minimize rpms
2) Tailgating trucks to get the drafting effect (although this is a bit extreme)
3) Turning the engine off at long stop lights
4) Accelerating slowly

Those suggestions are all counterproductive.

1. Shifting to neutral forces the engine to use gas to idle. Leaving the car in gear while coasting engages complete fuel cutoff until the engine RPM reaches idle speed again, which means you use zero fuel instead of idle fuel. It's the difference between ~80 MPG while coasting and infinity MPG while coasting. I've verified this with my Scangauge, and anyone can learn to discern the fuel cutoff and cutin with enough practice and sensitivity to their car. LEAVE THE CAR IN GEAR.

<snip>

Infinity MPG? In gear, the engine sure is running and burning fuel. It also is running at a higher rpm than if the car was put into neutral(idle).

Yes infinity.

Fuel combustion is not taking place. The engine is still going through all its cycles but there is no fuel being burned.

 

[dowxp]

I used to P&G, but then the data showed that running at 40-50mph in 6th is more fuel efficient (35-45mpg) than p&g

the only problem is the lack of data showing max efficiency at full throttle. if this were true, hypermiling wouldn't be so painful. I'd just push off in 1st, quick to 2nd, gun through to 3rd, and go straight to 6. but i don't have a good way of finding the empirical data from scan gauge. for now, i just grandma it to 35 and go to 6th.

 

[dowxp]

Originally posted by: mariok2006

Yes infinity.

Fuel combustion is not taking place. The engine is still going through all its cycles but there is no fuel being burned.

this won't ever happen unless the engine happened to be in high rev before you clutched-in. the engine needs fuel otherwise it will turn off.

the only time you'd have inf mpg is when you engine brake. and that isn't a good way of pulse and gliding.

 

[nakedfrog]

Originally posted by: Capt Caveman

Originally posted by: thomsbrain
The air conditioner in my Honda Accord uses 1.2 HP according to my Scangauge. Idle is ~6.8 HP with it off, and ~8.0 HP with it on. It takes roughly 25 HP to cruise at 60 MPH on level ground, which means the air conditioner increases the engine load by roughly 5%. Personally I'm willing to live with that if it means I get to be comfortable.

Originally posted by: Connoisseur
Yeah i believe hypermiling involves several, more "extreme", methods to make your car sip fuel. Some examples:
1) Shifting to neutral during downhills to minimize rpms
2) Tailgating trucks to get the drafting effect (although this is a bit extreme)
3) Turning the engine off at long stop lights
4) Accelerating slowly

Those suggestions are all counterproductive.

1. Shifting to neutral forces the engine to use gas to idle. Leaving the car in gear while coasting engages complete fuel cutoff until the engine RPM reaches idle speed again, which means you use zero fuel instead of idle fuel. It's the difference between ~80 MPG while coasting and infinity MPG while coasting. I've verified this with my Scangauge, and anyone can learn to discern the fuel cutoff and cutin with enough practice and sensitivity to their car. LEAVE THE CAR IN GEAR.

<snip>

Infinity MPG? In gear, the engine sure is running and burning fuel. It also is running at a higher rpm than if the car was put into neutral(idle).

Oh, man, you're about to open a HUGE can of worms.

 

[overst33r]

Originally posted by: dowxp

Originally posted by: mariok2006

Yes infinity.

Fuel combustion is not taking place. The engine is still going through all its cycles but there is no fuel being burned.

this won't ever happen unless the engine happened to be in high rev before you clutched-in. the engine needs fuel otherwise it will turn off.

the only time you'd have inf mpg is when you engine brake. and that isn't a good way of pulse and gliding.

engine braking IS taking place while coasting in gear...

 

[Sukhoi]

Originally posted by: dowxp

Originally posted by: mariok2006

Yes infinity.

Fuel combustion is not taking place. The engine is still going through all its cycles but there is no fuel being burned.

this won't ever happen unless the engine happened to be in high rev before you clutched-in. the engine needs fuel otherwise it will turn off.

the only time you'd have inf mpg is when you engine brake. and that isn't a good way of pulse and gliding.

Why exactly will it turn off?

 

[dowxp]

RE: engine braking IS taking place while coasting in gear...

that is correct, I didn't mean to say it wasn't

Originally posted by: Sukhoi

Originally posted by: dowxp

Originally posted by: mariok2006

Yes infinity.

Fuel combustion is not taking place. The engine is still going through all its cycles but there is no fuel being burned.

this won't ever happen unless the engine happened to be in high rev before you clutched-in. the engine needs fuel otherwise it will turn off.

the only time you'd have inf mpg is when you engine brake. and that isn't a good way of pulse and gliding.

Why exactly will it turn off?

because you need fuel to keep the engine turning, eventually the engine will lose energy and rpm will drop to zero (pretty fast, probably 1second). in fact, usually you can flip the car off and back on (without tripping the starter) and if the engine is still above idle rpm, the ecu will just act like nothing happened.

hopefully i'm not spewing bs. this is just my thinking and my experience with my car

 

[dowxp]

Originally posted by: mariok2006

Originally posted by: dowxp

Originally posted by: mariok2006

Yes infinity.

Fuel combustion is not taking place. The engine is still going through all its cycles but there is no fuel being burned.

this won't ever happen unless the engine happened to be in high rev before you clutched-in. the engine needs fuel otherwise it will turn off.

the only time you'd have inf mpg is when you engine brake. and that isn't a good way of pulse and gliding.

engine braking IS taking place while coasting in gear...

maybe i stated clutch-in wrong, i'm not sure what the correct terminology.

clutch-in -- physically stepping on the clutch, disengaging engine from transmission
clutch-out -- power to the wheel.

 

[overst33r]

Originally posted by: dowxp
RE: engine braking IS taking place while coasting in gear...

that is correct, I didn't mean to say it wasn't

Originally posted by: Sukhoi

Originally posted by: dowxp

Originally posted by: mariok2006

Yes infinity.

Fuel combustion is not taking place. The engine is still going through all its cycles but there is no fuel being burned.

this won't ever happen unless the engine happened to be in high rev before you clutched-in. the engine needs fuel otherwise it will turn off.

the only time you'd have inf mpg is when you engine brake. and that isn't a good way of pulse and gliding.

Why exactly will it turn off?

because you need fuel to keep the engine turning, eventually the engine will lose energy and rpm will drop to zero (pretty fast, probably 1second). in fact, usually you can flip the car off and back on (without tripping the starter) and if the engine is still above idle rpm, the ecu will just act like nothing happened.

hopefully i'm not spewing bs. this is just my thinking and my experience with my car

That's the thing, you don't need fuel to keep it turning. The wheels keep the engine turning (assuming you're in gear), you need fuel to make the wheels turn FASTER.

What I'm saying: No fuel is being used when engine braking. That is all.

 

[dowxp]

Originally posted by: mariok2006

Originally posted by: dowxp
RE: engine braking IS taking place while coasting in gear...

that is correct, I didn't mean to say it wasn't

Originally posted by: Sukhoi

Originally posted by: dowxp

Originally posted by: mariok2006

Yes infinity.

Fuel combustion is not taking place. The engine is still going through all its cycles but there is no fuel being burned.

this won't ever happen unless the engine happened to be in high rev before you clutched-in. the engine needs fuel otherwise it will turn off.

the only time you'd have inf mpg is when you engine brake. and that isn't a good way of pulse and gliding.

Why exactly will it turn off?

because you need fuel to keep the engine turning, eventually the engine will lose energy and rpm will drop to zero (pretty fast, probably 1second). in fact, usually you can flip the car off and back on (without tripping the starter) and if the engine is still above idle rpm, the ecu will just act like nothing happened.

hopefully i'm not spewing bs. this is just my thinking and my experience with my car

That's the thing, you don't need fuel to keep it turning. The wheels keep the engine turning (assuming you're in gear), you need fuel to make the wheels turn FASTER.

What I'm saying: No fuel is being used when engine braking. That is all.

oh. then we agree

 

[Chiropteran]

Originally posted by: randomlinh

Originally posted by: amdskip

Originally posted by: JLee

Originally posted by: Connoisseur
Yeah i believe hypermiling involves several, more "extreme", methods to make your car sip fuel. Some examples:
1) Shifting to neutral during downhills to minimize rpms

That's illegal in some places, btw...engine has to stay in gear while driving.

I don't care, I put my car in neutral when I'm going down hills just as long as I can maintain speed and no one is close to me.

and this is what i'm afraid people will do more and more... they think they're ok in neutral, and then can't react fast enough when an emergency does happen.

Does your car disable it's breaks in neutral or something? How does being in neutral different from being in any other gear?

 

[BlahBlahYouToo]

Originally posted by: thomsbrain
1. Shifting to neutral forces the engine to use gas to idle. Leaving the car in gear while coasting engages complete fuel cutoff until the engine RPM reaches idle speed again, which means you use zero fuel instead of idle fuel. It's the difference between ~80 MPG while coasting and infinity MPG while coasting. I've verified this with my Scangauge, and anyone can learn to discern the fuel cutoff and cutin with enough practice and sensitivity to their car. LEAVE THE CAR IN GEAR.

so at what rpm does your accord fuel cutoff stop? i.e. rpm's drop so low that the engine requires fuel to be injected to keep it turning?

 

[AbsolutDealage]

Originally posted by: Chiropteran

Originally posted by: randomlinh

Originally posted by: amdskip

Originally posted by: JLee

Originally posted by: Connoisseur
Yeah i believe hypermiling involves several, more "extreme", methods to make your car sip fuel. Some examples:
1) Shifting to neutral during downhills to minimize rpms

That's illegal in some places, btw...engine has to stay in gear while driving.

I don't care, I put my car in neutral when I'm going down hills just as long as I can maintain speed and no one is close to me.

and this is what i'm afraid people will do more and more... they think they're ok in neutral, and then can't react fast enough when an emergency does happen.

Does your car disable it's breaks in neutral or something? How does being in neutral different from being in any other gear?

It's not the brakes you are worried about, its the fact that you are essentially disabling your ability to accelerate. Depending on the emergency, you may be reaching for the gas pedal instead of the brakes. When you go to hit the gas, nothing will happen. That is the reason it is illegal in many areas to drive with the car out of gear.

 

[dowxp]

at the rate your car slows down due to engine load, areo, drag, you'd lose 10mph in like 7 seconds at 60mph+. whats the point? you'd have to accelerate again and again .. and i'd get annoyed and say screw it.

accord rpm idle is at 760-780. i wouldn't go below 1k when engine braking.

Originally posted by: AbsolutDealage
It's not the brakes you are worried about, its the fact that you are essentially disabling your ability to accelerate. Depending on the emergency, you may be reaching for the gas pedal instead of the brakes. When you go to hit the gas, nothing will happen. That is the reason it is illegal in many areas to drive with the car out of gear.

i wouldn't coast in neutral unless there is no one around you. just push the clutch in and be ready to pop the clutch if you have to.

 

[Chiropteran]

Originally posted by: AbsolutDealage
It's not the brakes you are worried about, its the fact that you are essentially disabling your ability to accelerate. Depending on the emergency, you may be reaching for the gas pedal instead of the brakes. When you go to hit the gas, nothing will happen. That is the reason it is illegal in many areas to drive with the car out of gear.

The same is true when you drive in the highest gear at 2k rpm- you step on the gas and nothing happens, you have to down shift to really accelerate.

 

[JeffreyLebowski]

Someone has a sig that I like it says:
I brake for hypermilers.