hypermiling

stratos

I am sure most people on here have heard of this or there probably was a thread I missed. I have been trying some of the techniques. It's amazing what can be achieved with even the simple steps.

I have always stayed back and and watched the traffic trying to avoid using the brakes by driving well back. Adding coasting to this and switching off the engine at lights really dramaticly improves things. People seem divided on coasting(with the engine running) is it safe or not, I don,t see a problem with it. The whole Idea of hypermiling is hang back and watch whats going on more closely, so not being in gear should not be a problem.

The real enemy is idling I have been doing this for a few weeks and idling in traffic or just while you put your belt on really ruins the results. Slow acceleration and the way you approach a hill gives great results. Coasting with the engine off but acc on is a big saver, I might use it in rural areas, not a fan of it though.

I managed to get 45 mpg on a two litre car and it was a good experiment. However driving like a granny to save a few bob is a pain and I see petrol is going down again. Now what rpm does the cam come on at again.:)

Oh just to add I wonder in the long term if the value would be offset by premature wear of the starter moter, and drive train components i.e. the extra clutching and gear shock matching of coasting etc.

unnameduser

I would def agree that making an extra effort concentrating on fuel economy definately has a great effect. I don't go to the extremes of turning off the engine but by simply accelerating slowly i manage to get 55MPG from my 1.9TDI 130BHP Passat driving from Nenagh to Limerick each day. I was only getting about 45 before.

Steve

stratos wrote: »

Coasting with the engine off but acc on is a big saver, I might use it in rural areas, not a fan of it though.

Coasting with the engine off = no servo assist on your brakes = can't stop in an emergency.

Please don't say you've actually done this. :eek:

mthd

life's too short tbh :rolleyes:

conneem-TT

I would say that coasting with your engine off is a very bad idea, as you would not be in total control of the car.

My car cuts the fuel supply if you coast up to a stop in gear with your foot off the accelerator, don't know about anyone elses.

JHMEG

Coasting with the engine off is only on long-ish straight stretches with good visibility ahead. It's not done around town or on twisty roads.

There is usually enough reserve in the brake booster for one or two hard stops with the engine off.

Coasting is an inherent part of hypermiling, as is easy driving and anticipating traffic. The term hypermiling was coined by Wayne Gerdes of cleanmpg.com.. they have a interesting register of hypermilers. Interesting to see a Prius average 100mpg over the last 2,600 miles for example.

peasant

some of the hypermiling tips that i've come across in the internet are just plain dangerous, coasting with the engine off is one of them. Others are very inconsiderate of other drivers (like matching your speed to the best efficiency of the engine regardless of the traffic around you ...that usually results in what others would call dawdling)

Just cutting down on hectic driving round town and in heavy traffic will save you enough fuel so that you don't have to feel guilty when you floor it on the next stretch of open road

tvr

I think Audi have tested a traffic light system in Inglestadt. There are sensors on every traffic light that broadcast to the car. The computer then tells you what speed to drive at the avoid getting red lights etc.. the traffic management system also sents you on the most optimal route. Seemingly it increased mpg by over 25% and significantly reduced the co2 ouput because there very little braking.

Thought that was a really good idea. As a country we are small enough so would be great to get this tested and implemented in Dublin etc..

JHMEG

peasant wrote: »

some of the hypermiling tips that i've come across in the internet are just plain dangerous, coasting with the engine off is one of them.

I'd actually like to know why some people think that's dangerous when it's done on the open road with good visibility etc, because
a) it's done with the gearbox in gear, the clutch pedal to the floor and the ignition on. Engine can be clutch started in an instant
b) The brake booster has enough reserve for one or two full force stops anyway
c) At speed power assisted steering isn't required

The only thing that you can't do is floor it, as you've to clutch start first.

peasant

JHMEG wrote: »

I'd actually like to know why some people think that's dangerous ....

There is quite some potential for gettin it wrong, especially for the inexperienced driver.

You could make the mistake of turning the ignition off completely and the key all the way to steering lock.:eek:

Letting speed get too low could cause you to stall the engine on re-start or get your gears wrong and go into a skid

JHMEG

peasant wrote: »

There is quite some potential for gettin it wrong, especially for the inexperienced driver.

You could make the mistake of turning the ignition off completely and the key all the way to steering lock.:eek:

Letting speed get too low could cause you to stall the engine on re-start or get your gears wrong and go into a skid

It's a mechanically propelled vehicle. There's potential for getting lots of things wrong and doing serious damage. Doesn't mean they shouldn't be done tho.

Anan1

JHMEG wrote: »

I'd actually like to know why some people think that's dangerous when it's done on the open road with good visibility etc, because
a) it's done with the gearbox in gear, the clutch pedal to the floor and the ignition on. Engine can be clutch started in an instant
b) The brake booster has enough reserve for one or two full force stops anyway
c) At speed power assisted steering isn't required.

Will ABS and ESP function when the engine's not runnning? Even if they did, a car with dead PS is a completely different thing to a car with no PS - the steering will be a lot heavier. Most people will be unable to control it as well in a panic situation as they would if the engine was running.

JHMEG

Anan1 wrote: »

Will ABS and ESP function when the engine's not runnning?

My ABS does as it works off a high pressure tank. EBD I can't say for definite but since it is Electric I don't see why not.

Anan1 wrote:

Even if they did, a car with dead PS is a completely different thing to a car with no PS - the steering will be a lot heavier. Most people will be unable to control it as well in a panic situation as they would if the engine was running.

I wouldn't agree with that about the PS, based on personal experience. In addition a lot of PAS these days are electric and work with the engine off.

The bottom line is it's not safe to coast just about anywhere. It's like anything else when it comes to driving: it should only be done when it's safe to.

Steve

If the worst did happen and the road was in any way slippy (e.g. new rain) then ABS would put paid to the servo resevoir in an instant. Trying to bump start in the middle of all that could also cause the wheels to lock. Not a nice thing to happen in the middle of trying to steer around the deer that just appeared in front of you.

I know that's an unlikely situation but "unlikely situations" are generally when you need everything on your side.

Fair enough, a well experienced driver might cope with that, someone with little experience would end up in the ditch.

The other thing I want to be sure of is: do the airbags still work with the engine off?

JHMEG

SteveC wrote: »

If the worst did happen and the road was in any way slippy (e.g. new rain) then ABS would put paid to the servo resevoir in an instant. Trying to bump start in the middle of all that could also cause the wheels to lock.

Absolutely. Probably best not to do it in those conditions.

Anan1

JHMEG wrote: »

Absolutely. Probably best not to do it in those conditions.

I think the point here is that road conditions can go from fine to critical in the blink of an eye.

Jimbo

There was a big piece in USA Today a few weeks back on hypermiling.
It's almost developed into some kind of sport across the water.
These guys can routinely get 100mpg. Penny pinching if you ask me.
Link here

JHMEG

Anan1 wrote: »

I think the point here is that road conditions can go from fine to critical in the blink of an eye.

Of course they can, I agree. Most accidents are as a result of bad decisions made by drivers.

Nonoperational

My God if anyone actually does this they should just sell up the car and buy an electric scooter or something. Ridiculous. Ruining the fun of driving to save a few euro. People that do this kind of rubbish are the kind of people that sit in a dark sitting room every night with no lights or TV to save the electricity bill. I've no problem with driving economically within reason, its smart. But some of the suggestions on the hypermiling sites are obviously made by idiots that couldn't tell a car from a donkey.

And it is obviously more dangerous coasting with the engine off! Cars were amazingly designed to be driven with the engine on. Crazy isn't it.

JHMEG

I'm quite looking forward to giving it a serious lash in the IMA. Want to see if I can beat my personal best of 89.9mpg on a reasonable length trip.

biggus

Any car nut that drives a prius for more than a few days will learn lots about how to achieve good fuel economy and what effects it drastically. Driving a prius economically is like riding a bicycle where momentum is all important and going up hills is a killer.
Techniques learnt in a prius ,can then be applied to any car; with best results in a guzzler.

gpf101
Ruining the fun of driving to save a few euro. People that do this kind of rubbish are the kind of people that sit in a dark sitting room every night with no lights or TV to save the electricity bill.

I think the point here is that even car fanatics will hypermile while commuting so they can still have fun drivng in short bursts at the week-end. Also achieving good mpg is part of the "what if we ran short oil, could i still drive" ? syndrome

I know that, if my wifes Prius was full of petrol at the start of a crisis/shortage .. we could probably make it last three months. Also the furthest I got on one gallon was 73 actual miles.

Nonoperational

Ya I agree everyone will at times want to get max MPG from their car, for some reason I just got a bit annoyed about people obsessing to the exent of turning on and off the car every few minutes to save a few quid on petrol. Had to get a rant in!

pburns

I try and maintain momentum, plan ahead but really that's about it. It can be fun if you're not in a rush to try and get a decent l/100km figure on the computer.

I don't understand guys here who seem to have cars with decent power/acceleration and then start pussying around trying to save fuel though. Nor do I really understand those who buy a car with air-con and refuse to use it in a sweltering hot cabin.

I can get about 6.4l/100km from my Legacy if driving it reasonably easy, keeping revs down etc. - no crazy hypermiling techniques or anything. If I drive it making full use of it's mid-range poke and with air-con blowing I get 7.0l/100km which is still decent IMO. If I wanted to meander around at glacial speed and save fuel I would have bought a 407 or C5 with the 1.6HDi engine.

mickdw

Anybody turning off the engine of the car travelling at any speed should be shot. Its pure madness and im sure the traffic cops would have something to say about it too.
I once let my car roll forward from parked by a few metres and it was difficult to stop ( lots of force required) so I dont know about this theory of a pressure reserve in the brake system.
Buy a f**kin moped if ya cannot afford to leave the engine running or if you can afford it and still insist on turning off, you should have your license taken away.

Neilw

If people are that worried about getting an extra few MPG to save money why don't the just leave the car at home for a few short journeys and walk/cycle/get the bus instead.

Neil.

JHMEG

Very interesting article here. Part of hypermiling is inflating tyres to max pressure. The cleanmpg people quote this Police article that says as well as improving economy, increasing pressure improves wet grip and general performance.

http://www.officer.com/web/online/Editorial-and-Features/Driving-Under-Pressure/19$27281

Regardless of what vehicle you have, use the maximum pressure listed on the sidewall. Higher pressure results in better performance, decreased tire wear, and it lessens your chance of hydroplaning at a given speed.

mickdw

As someone said previously, most modern cars use no fuel, absolutely none when you lift off the accelerator. The fuel supply to the engine is stopped and the momentum of the car is used to keep the engine running. I would also say that timing or whatever is controlled to keep the resistance in the engine to a minimum in these situations, so can someone explain why they turn off the car. If there was any advantage to be gained in this, wouldnt BMW efficient dynamics equiped cars have a system is shut down engine on the move and keep basics like brakes and steering live. They only allow the cars to shut down when at a standstill for one simple reason. You cannot be in full control without engine power.

JHMEG

jimbo78 wrote: »

There was a big piece in USA Today a few weeks back on hypermiling.
It's almost developed into some kind of sport across the water.
These guys can routinely get 100mpg.

Very good article. Well worth the read.

jimbo78 wrote:

Penny pinching if you ask me.

So is buying a diesel! :D

JHMEG

mickdw wrote: »

so can someone explain why they turn off the car.

When decelerating and the injectors are off a huge amount of inertia is lost through keeping a dead engine turning over. It really is a bad use of energy. Most hybrids have Valve Pause Systems (mine does) to try to limit the effects of it a bit where valves stay open to avoid unnecessary compression.

mickdw

JHMEG wrote: »

When decelerating and the injectors are off a huge amount of inertia is lost through keeping a dead engine turning over. It really is a bad use of energy. Most hybrids have Valve Pause Systems (mine does) to try to limit the effects of it a bit where valves stay open to avoid unnecessary compression.

If you read my last post you will see I mentioned about altered timing to reduce resistance within engine, reducing compression is exactly what I was talking about and modern engines are intelligent enough to do that. The energy lost is not worth considering and Im sure the extra mars bar you would need to eat to stamp on the brake pedal when engine is not running would more than cancel out any gain
So why would anybody turn off the engine?

E92

Neilw wrote: »

If people are that worried about getting an extra few MPG to save money why don't the just leave the car at home for a few short journeys and walk/cycle/get the bus instead.

Neil.

Yes indeed.

Hypermiling is downright dangerous, as well as being highly inconsiderate to other road users.

Not only that, but I've now found why some hybrid owners are able to achieve the type of mpg figures that hybrid fanbois say they can achieve.

But fear not we'll get told in a minute that when you drive them normally like they do in car magazine tests and where they get beaten by diesel on a regular basis that the car mags are "all wrong" or that their testing method is "flawed" or whatever excuse to avoid the fact that diesel does what hybrid does for mpg, but there are no compromises like tyres designed for economy above grip, CVT boxes, thinner glass so the car is noisier etc.

At least people who promote diesel as getting hybrid like mpg don't do all these utterly dangerous and inconsiderate techniques. Since we have a diesel at home, I can tell you that they really do deliver the goods on mpg, and you don't have to hypermile, slow down or anything; just drive it like normal and they still seem to save you money.

How come diesel does hybrid economy without all the compromises?

Imagine what mpg a non hybrid car could achieve if we decided to put our lives at risk.

But I like driving and I don't like taking forever to get wherever I want to go, so I'll stick with my not very economical method of driving thank you very much. I didn't acquire a not at all CO2 friendly petrol straight 6 with RWD so that I could save a couple of polar bears. No, because you only live once and because I enjoy driving, I acquired it so I could have something that puts a smile on my face when I go driving and loves to be revved. I did try the old techniques for saving fuel. But I gave up quickly since I was only getting around 5 mpg more but had lost all the fun of driving in the process. The bus provides fun free motoring too but with much more environmental benefits. So I'll do that instead should I build up a bit too much of a carbon footprint thank you very much.

In the meantime those who are that concerned about the planet, running costs etc, please go and use the bus, train, Luas, DART or whatever. You'll free up traffic, which means the rest of us will get there quicker, fewer cars on the roads = less CO2 and you'll save your carbon footprint, as well as your wallet a packet. Not only that but since you weren't going fast in the first place, you won't get there any slower either, and there won't be the stress of driving thrown in either.

Steve

E92 wrote: »

No, because you only live once and because I enjoy driving, I acquired it so I could have something that puts a smile on my face when I go driving and loves to be revved.

+1

That's what it's all about for me as well.

JHMEG

Well there goes another thread killed by the flat earth society. And here I thought we were going to have a bit of an interesting discussion, and not a lecture on the dangers of being different.

@stratos, the poeple on the cleanmpg forums are cool. If you'd like to know more etc that's the place to go.

That's me done with this thread.

Steve

JHMEG wrote: »

Well there goes another thread killed by the flat earth society. And here I thought we were going to have a bit of an interesting discussion, and not a lecture on the dangers of being different.

@stratos, the poeple on the cleanmpg forums are cool. If you'd like to know more etc that's the place to go.

That's me done with this thread.

Who's lecturing - there's two sides to every discussion.

Please don't stop now, I am interested in this.

Matt Simis

My cars get pretty bad MPG. One of the things I was trying out was flooring it at the bottom of a steep hill (a brief blip to 75mph) then coasting the entire way up the hill. To clarify the hill is about 70m long, quite steep and noone around me.

I havent checked all the numbers, but it would be interesting if a burst of acceleration and terrible MPG offsets maintaining say 50mph up the hill. Also of interest was the fact the 2 cars decelerate strangely different:

2.6ton Phaeton goes from 75 to 49mph at the peak (Tiptronic)
1.7ton Allroad goes from 75 to less than 40mph just before peak (Tiptronic)

I would have thought the heavier car would slow down faster.. unless its inertia keeps it moving longer?


EDIT- In the interest of true Hypermilling topics, another HM tactic is to cruise in the "wake" of a large truck, staying as close as possible (although over 1car length away). This is to allow the truck to face wind resistance and punch a hole you follow in (ie drafting). I dont actually think this is as dangerous as it sounds as you read over it it, its basically driving slowly behind a slow large vehicle.

Steve

Matt Simis wrote: »

I would have thought the heavier car would slow down faster.. unless its inertia keeps it moving longer?

The heavier car has greater moment of inertia = it will take longer to slow down.
It also takes more energy to accelerate it.

force = mass * acceleration

peasant

Matt Simis wrote: »

My cars get pretty bad MPG. One of the things I was trying out was flooring it at the bottom of a steep hill (a brief blip to 75mph) then coasting the entire way up the hill.

The trick is not to coast (certainly not uphill) but to carry enough momentum so that you can maintain speed (or close enough) while keeping a feathered foot on the accelerator. Ideally you want to do this at the revs where your engine has maximum torque to get the most out of very little pressure on the gas.

I have to push my yoke up a very steep hill every day on the way home.
I start the hill in second (no choice, there is a crossroads before it) and keep the acceleration very light at the point where the turbo is at full blow but the accelerator is only down one third or so until there is a slight dip, shift into third there and again with very light pressure on the gas make it to the top where I finally shift into fourth.

I could whip the car up there, getting into fourth before the brow ...but you can actually hear the fuel gurgle trhough when you do that

Whipping the car before you hit the hill would have a similar effect.

JHMEG

SteveC wrote: »

Who's lecturing - there's two sides to every discussion.

There are several on this thread.

Matt, Steve C's maths are pretty much correct. In your case there's no such thing as a free lunch. Altho when you're coming back down that hill you could coast and recover a lot of energy.

Drafting, or draughting I think on this side of the Atlantic, is actually very effective from my own experience. I did it just once, in the Integra (which never did more than 30mpg, even on a run), from Dundalk to the M50 and managed to get 60mpg! I was shocked! It's not that dangerous as big lorries can't stop that quicky, but it didn't stop me from bricking it anyway. If I had hit him iirc it would have been his back wheels, as the Integra was fairly low

peasant

Matt Simis wrote: »

EDIT- In the interest of true Hypermilling topics, another HM tactic is to cruise in the "wake" of a large truck, staying as close as possible (although over 1car length away). This is to allow the truck to face wind resistance and punch a hole you follow in (ie drafting). I dont actually think this is as dangerous as it sounds as you read over it it, its basically driving slowly behind a slow large vehicle.

I used to do that with my old, tragically slow camper (50hp diesel) on long motorway trips ...that is I tried it a few times.

DON'T DO IT ! It is ridiculously dangerous !

Travelling at 80-90 km/h (average truck speed) with a distance of a mere 5- 7 meters is suicidal. Those trucks have pretty good brakes and you're travelling totally blind behind them. If the trucker has to throw anchor, you will hit the truck before you're even able to hit the brakes.

80 km'h may feel slow ...but believe me it's way too fast to keep such a small distance. I learned that lesson after being about 5cm away from making contact with the back of an articulated lorry. Thankfully he only tapped the brakes hard and then sped up again ...otherwise I probably wouldn't be here to write this.

Matt Simis

Cool stuff, Ill try the less dramatic feathering next.

On the maths, I dont question force = mass * acceleration and a re-read of mass vs weight on Wikipedia answered my own question.

PS: I dont do any actual Hypermilling other than laying off the brakes, definately not drafting as I hate not to be able to see the road ahead.

JHMEG

Sound. I actually don't do any really either, apart from trying a few things out now and again, and have never done any of it in the Civic IMA. Hence I'm looking forward to trying!

Steve

On the subject of 'draughting' or slipstreaming, I've read that it's just as effective to hang close behind a large truck in the other lane on a motorway/ DC. This solves the braking distance / view ahead problem.

Be polite and move in if you get traffic behind though.

caesar

E92 wrote:

I didn't acquire a not at all CO2 friendly petrol straight 6 with RWD so that I could save a couple of polar bears.

Something for my sig

Matt Simis wrote: »

On the maths, I dont question force = mass * acceleration

ROFL....you'd have some explaining to do if you did!!


Anyway I heard some guy on the last word a few weeks back, he was some world champion for this thing. I listened to it out of curiosity but I couldn't listen to him again, talk about removing all of the the enjoyment from driving. I think they should use that as some sort of definition for the term hypermiling .

Mr Benevolent

I'd actually like to know why some people think that's dangerous when it's done on the open road with good visibility etc

One more point about engine-off coasting - when the engine is off the airbags and pre-tensioners won't fire in a crash.

Steve

Confab wrote: »

One more point about engine-off coasting - when the engine is off the airbags and pre-tensioners won't fire in a crash.

I asked that earlier - I'm not sure what you say is true.
When the ignition is on, they're probably active.
It they weren't then an accident caused by stalling would cause them not to deploy - I find that hard to believe.

E92

Matt Simis wrote: »

EDIT- In the interest of true Hypermilling topics, another HM tactic is to cruise in the "wake" of a large truck, staying as close as possible (although over 1car length away). This is to allow the truck to face wind resistance and punch a hole you follow in (ie drafting). I dont actually think this is as dangerous as it sounds as you read over it it, its basically driving slowly behind a slow large vehicle.

I think it is extremely dangerous. What if the car behind you wants to overtake on a single carriageway road?

There should always be enough of a gap so that if the car behind you decides to overtake and for some reason they need to pull in just in front of you, where are they supposed to go?

Oh and being that close to the truck means you won't be adhering to the most important rule of all for road safety : the 2 second rule.

Matt Simis

E92 wrote: »

I think it is extremely dangerous. What if the car behind you wants to overtake on a single carriageway road?

There should always be enough of a gap so that if the car behind you decides to overtake and for some reason they need to pull in just in front of you, where are they supposed to go?

Oh and being that close to the truck means you won't be adhering to the most important rule of all for road safety : the 2 second rule.

Hey, Im not advocating it, just repeating stuff from a list of 14 or so Hypermilling "skills"!

JHMEG

Matt Simis wrote: »

Hey, Im not advocating it, just repeating stuff from a list of 14 or so Hypermilling "skills"!

The hypermiling guys appreciate drafting, but don't advocate it on safety grounds.

JHMEG

SteveC wrote: »

I asked that earlier - I'm not sure what you say is true.
When the ignition is on, they're probably active.
It they weren't then an accident caused by stalling would cause them not to deploy - I find that hard to believe.

I'd be inclined to take it a bit further.. when the Vehicle Speed Sensor is registering a speed above which the airbags will fire on an impact I'd say the computer will fire them, engine/ignition on or off. Why would a safety feature be turned off just because the ignition is.