Saving Fuel While Driving Downhill

Trains are already doing it in the UK - maybe elsewhere to.

You may well do this, however if your vehicle has power brakes or power steering your effort to control the vehicle will be multiplied. Having to make a quick maneuver to avoid an animal will be further complicated and you might cause an accident.
Save fuel? Yes. Higher risk? Yes. If you do have an accident it would also be difficult to explain to your insurance company why you shut off the engine...

Well first off, don't you mean "engine" not "motor"?

One thing to keep in mind when the engine is not running you lose power steering in most all modern vehicles. By simply pushing in the clutch or (if an automatic transmission) shifting into neutral you can drift a long way without the dangers of power steering loss.

Another good tip is to drive slower and try your best to never use your brakes around curves. When coming to a stop light, if it is red, slow down a ways back and hopefully by the time you get to the light it will have turned green (color and light system may differ from country to country, but the theory is still sound) and by keeping the car moving you have saved gas.

Anyway, this post could go on forever but if you want more info Google "hypermiling" and you will get nearly limitless resources, but as always, just try to keep the rubber side down.

Used to fill up every 6 days, now only have to fill up every 21 days

job outsourced, laid off, less road rage, less politics

Regenerative braking is the safe alternative to this.

Interesting. Just Googled the term "regenerative braking" and came across this page from the Rocky Mountain Institute. My commute takes me up and down several mountains, so hybrid-electric technology just became even more interesting to me.

This is another approach - which has been discussed here in other threads (as you've no doubt seen).

You're describing "Hyper-Miling"

http://www.google.com/search?q=hypermiling

Must be some big hills where you live in order to save fuel. With the engine running there is little fuel being used when going down hill.

Do you turn off the engine at red lights also?

Both these actions are violations in most states of the USA

It will remain to be seen if in fact you are saving money. The one device that you are not considering is the starter and flywheel. Lets see the starter and the towing fee could be pretty pricey let alone a flywheel replacement.

Read this article from a local High School group that won the Mileage Challenge with a vehicle that went 2,843 miles on ONE GALLON of gas.

http://www.msnbc.msn.com/id/24111771/

It can be done but not with what we have become used to with the old lower Gas prices.

This sounds good, however there is a safety factor here. When the engine is switched off and the car is coasting down hill, the power assisted stearing won't work. The result is a much stiffer stearing that may cause loss of control if there are curves or bends in the down-hill path. Frankly, the savings is not really worth having an accident and injuring yourself or other road users.

hello I am from the Philippines... I been using this style turning off the engine on a downhill and smooth flat surface for almost 4 months (after the surging price of fuel)...my car is a toyota corolla 1990 it has no power steering so the one mention above is not applicable..I increase my millage from 10km/liter to 15km/liter (50% improvement on millage)..but one thing I notice is that the brakes after the second press down will be tougher (hydovac problem) this was the result of supply of air to the brake system...but other that it has no problem and work for me...my advise is be careful and learn and anlayze first your route before applying this..since I use my car from work to home so I already mastered when I will turn-off the engine and when to turn in on again...starter problem?i dont think so before the car comes to stop put the shift to 3rd gear and put the ignition to on and lift slowly the clutch it will turn on the engine instantly...accident?i have not yet enocounter any after I use this technique...be safe master the road first before doing this...and also get use to the car that always honking behind you when you to this...thanks...

Hi Guest- I give you a GA - you are doing everything I am!. Certainly vac assist brakes are harder, but still work- & let's face it- we ain't doing any great speed!. Purists will say "angel gear"- but as you have said choose locations- I feel this type of thing will become increasingly important as the Global financial meltdown accelerates!.

It's not just the loss of steering control when the engine is shut off.

It's harder on your breaks especially if you have to stop suddenly.

The engine also assists in slowing the car down during the breaking process due to engine compression.

To skip safety just to save some money on gas is just not very smart. I don't car if you are jobless. Being jobless just means you really won't be able to afford any medical costs and/or penalties if something should happen.

Another factor to think about in the cost issue is that shutting down your car and starting it up all the time on hilly roads is harder on the engine and what ever money you save on gas is just going to come out in mechanical repairs which hits you as a big lump sum all at once.

The DKW cars had a one-way-drive coupling between the engin and gearbox which could with cable operation be locked also; Thus, when going downhill the engine idle if you do not accellerate.

Cars with a "Bendix" overdrive also had this.

These where feulsavers.

I would never switch engin off going down hill; It is wasting the power needed to restart engine and is really dangerous!...No powersteering and hard brakes when vacuum in brake booster is depleted. Some-one do-ing this might just accidentally switch completely off and lock the steering!!!!!!

What sort of idiots do you think we are?!!!. We understand autos- how to drive & safety!!. Your statements are directed at the lowest mentality people- who should not be driving anyway!.- but should be walking(such as women, oldies, iggerants- really!- my dog could drive safely down a hill with the engine switched off!-(he often drives me home when I am pissed!)- Cheers!.

Neil Kwyrer, GA from me. Some people just love to pontificate. If these people had their way we would all be wearing safety helmets, safety glasses and knee pads when eating dinner

Regards

Mr. W.A Snow

If these people had their way we would all be wearing safety helmets, safety glasses and knee pads when eating dinner

If there was even the possibility, say 1in 10,000, that I might kill or at least hurt people maybe it's a good idea. Although I gotta say that most of those who posted on this one did not read any of the other posts (shame on you) before responding, it's almost all the same thing!!!

If you really want to save gas go buy a scooter! Just always remember everyone, safety first-accidents later

The comment about "women and oldies" is out of line and should not have been posted. You can have personal views on age, sex, or race but this is not the place to voice them.

BiomedWV, I am sure that Neil Kwyrer was saying this "tongue in cheek" and it was not meant to be serious (well that is how I read it anyway) or do you actually believe that his dog drives his car home when he has a few beers ?

Perhaps you should learn to see the lighter side of things.

Regards

Mr. W.A Snow

aKSHALLY i AM OLD, IGGERANT, a pisstank(Not a woman!)- it is my dog who is the clever one- he actually posted the original message!. After I discovered this, he allowed me to print this( I had to give him several bribes in the form of tasty raw meat)- oh no- here he comes!(bark, growl, snap, bite- yelp!) - yep I'll be good now Inky!.(A black kelpie) Cheers.

GA, it's hard to argue with good logic like that.

BiomedWV,I find it hard to understand your agreemnet with emc_c . I am truly puzzeled (I hope you see that I am being sarcastic).

Kind Regards

Mr. W.A Snow

I hope you see that I am being sarcastic

Yes I see, your use of the emoticon makes your point. And I hope that you and NK truly take an understanding of what emc_c is saying with the post. Not one of the posts I read suggested stupidity on the part of the original poster, but were just trying to ensure safety (although just one or two posts on that would have sufficed instead of everyone saying the same thing).

Oh thank you for calling me intelligent!- actually I am dumb & getting dumber by the day the more alcohol I drink-!- but I keep trying to freshen up my few remaining brain cells!-utopian society?- wot has that got to do with our capitalist society?- I merely suggested a means whereby responsible drivers could save fuel- it is amazing- when you look for hills you can coast down, they are everywhere!(providing the driver has enuff sense to do it safely!). Which you suggest is not possible- well these inept people should not be driving anyway!. This is why the coppers target the "average" driver with "average" tests- this completely ignores safety, capability of the worst as against the best- to an average!- all for convenience & revenue raising!. To sum up- ALL STOOPID DRIVERS- DO NOT COAST DOWN HILLS!!!.

Some older cars also activated the steering lock when the engine is turned off, some also did it if the engine stopped due to an engine malfunction or running out of petrol etc. !!!!

Yep. When I was a kid (and much, much smarter than anybody else), we'd go to the top of the mountain, turn off the engine, put the car in neutral and see how far we could coast before getting scared enough to put it back in gear (and blow a huge flaming backfire). I did it one night in a car with locking steering and was about where the guardrail would have scraped the car had there been a guardrail before I got the damn thing unlocked.

I tried this once driving my Dad's new pickup. He was riding with me and almost cold-cocked me for doing it . It seems that some cars with automatic transmissions will not tolerate coasting in neutral without the transmission pump operating, causing damage. I guess it depends on what coasting speed you're talking about, but I've never tried it since.

Dear Sir,

I can't make out exactly as to what message you want to convey to esteemed readers of CR4. But I suppose it is on energy conservation SIR.

Like you most of the professional drivers who are cost conscious and who are born energy conservationist, they do coasting and save the atmosphere from getting polluted to the extent possible as well as save the fuel too by switching off the ignition control during the car's downward journy.

In fact I used to apply same technique nearly 11 years back during my last LTC tour of South India covering 6728 Kms in old Premier Padmini car which was driven by me alone and my wife was acting like a navigator for the entire tour.

If all employ similar technique it will be a big saving of fuel.

Regards,

Ulhas Pradhan

Now with a car that gets 20 miles per gallon driving on a flat surface, and 10 mpg going up hill, the same car will get infinite (INF) mpg going down hill with the engine off. What, then, is the average mpg? (20 mpg + 10 mpg + INF mpg)/3 = INF mpg

Why doesn't this work in real life? I've stumped a few people with this, including accountants (although the accountants like the real-life application for adjusting month-end financials!)

Most modern cars effectively do this anyway...the fuel injection is computer controlled, If the wheels are trying to turn faster than the enge the computer will stop squirting fuel in.

My little Nissan Micra has a fuel consumption disply which shoots up to maximum if I take my foot off going down hill.
It's an automatic so virtually no engine braking.

Del

This has been tackled before. My stand remains the same:

Safety is non-negotiable. Keep the engine running when going downhill. It's not just your life but others as well.

My commute took me over some big hills and a small mountain. It was mostly downhill on the way to work and mostly uphill on the way home. I coasted as much as I could on the way down and so got about 30mpg going in to work (my small SUV shows me my avg mpg). On the way home, I would get around 22mpg going back up all of the hills.

My average mpg for "flat" surfaces (start/stop non-highway driving) is about 22mpg and I get about 27mpg on the highway. The coasting definitely helped improve my gas mileage!

This is a correct statement, a more fundamental view is to look at it like this:

Basically, in order to make correct and efficient use of your energy (gas) you don't need to cut down on acceleration (throttle) as much as you have to manage your braking...

In your example, you coast the car down the hill, which is fine, but you should focus on using the brakes less, and having less throttle necessary to power the car...

So don't ever use brakes! (Just kidding kids).

Didn't know this simple message meant so much to so many!

No power steering, no power brakes, possible steering column lock (if car has that anti-theft feature) are dangerous.

It takes alot of fuel and is rough on the engine when you start it.

Also, modern cars with advanced fuel injection don't use any fuel going downhill. The module realizes that there is no load on the engine and cut off any fuel injection. You'd actually use more gas putting it in neutral and having the engine idle downhill.

Well my last fuel usage using coasting- mpg from 39.5 to 47.5- iffen I thought it was hard on the engine I wouldn't do it!- my engine has done 704,000 kms- still runs like new- doesn't use oil- 1978 Isuzu 1.6l. Regards from an uneddicated, iggerant , old Bassid!.