Coasting and saving fuel

Got my road tax renewal notice today and enclosed was a leaflet from dept of transport on how to save money driving.

One tip was: 'dont coast downhill or towards the lights in neutral as this uses more fuel! Stay in gear and ease off the gas gently to reduce fuel flow to the engine to virtually zero.'

I read somewhere new engines are designed not to use fuel on the overun (decelerating using the engine) would this apply to a 2002 Toyota Corolla ?

Reply to
john ryan
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It would apply to pretty much anything with fuel injection and an ECU, so yes. The saving would be pretty trivial though.

As always however, the best way to save fuel is to not use the car! Walk if possible on short journeys, and try to plan trips so you can carry out a number of tasks in one journey.

Chris

Reply to
Chris Whelan

Since when did we 'ease off the gas' in the UK?

Reply to
Dave Plowman (News)
[...]

Perhaps we always did, but just didn't know? ;-)

I've heard driving instructors use the term 'more (or less) gas' to learners; I imagine that it's for brevity.

Chris

Reply to
Chris Whelan

Because it's one syllable instead of two for petrol or diesel, and covers both fuels? ;-)

Reply to
Gordon H

Great. Start learners off with the wrong term before they know the correct one.

Reply to
Dave Plowman (News)

No LPG - which is a gas?

Reply to
Dave Plowman (News)

it has been taught as 'the gas ' for 38 years to my certain knowledge.

Reply to
Mrcheerful

costing is illegal.

Reply to
Mrcheerful

If you switch the engine off while coasting, it doesn't use any fuel!

Reply to
The Revd

Not hear it hasn't. ;-)

Reply to
Dave Plowman (News)

Actually it more complicated than it seems. Nearly all fuel injected cars will have an overrun fuel cut off which means that they use no fuel on the overrun as opposed to a trickle of fuel when coasting.

That said, with no fuel being burnt, there will be increased drag so your car will decelerate faster. On a gentle hill that you might be able to coast down, if you leave it in gear you will actually have to use a certain amount of throttle to maintain the speed that you could have achieved freewheeling.

Depending on the length and duration of freewheeling, you could use less fuel with the engine idling than the fuel required to maintain road speed on a gentle downwards incline.

I know that by judicious use of freewheeling I was able to improve the economy of my diesel Touran but it had a DSG gearbox which made it very easy and smooth to slip between drive and neutral.

As Mr Cheerful has pointed out though, it is actually against the law.

You might like to look at this site.

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Tim

Reply to
Tim+

Oh, this old chestnut again.

No, it isn't illegal.

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(left hand column, beneath the diagrams of the cars)

Reply to
Mike P

The company costing dept will be shut, that should save some costs.

Reply to
Peter Hill

Ah, well you obviously wheren't listening ;-)

Reply to
Duncan Wood

There is more complexity.

The overrun fuel cut on petrol engines is triggered by the throttle being shut so the idle switch is on with the engine rpm higher than the idle soft landing rpm. Some may also detect gear from speed and rpm inputs. The soft landing rpm is usually around 1500rpm. RPM lower than that will switch fueling on so it doesn't stall when/if rpm drops to idle.

Select a gear that keeps rpm up around 2000. A gear that runs engine faster will be excessive drag - engine braking rather than easing off and not fuel efficient.

If you are lame about lifting off and obey the GOV instruction "ease off the gas gently", then fuel will still be supplied as the idle switch isn't ON until foot is fully off the throttle.

Diesels can't call it a throttle pedal as Diesels don't have throttles. Governor pedal? Demand pedal? Oil pedal? Smoke pedal?

Reply to
Peter Hill

In message , "Dave Plowman (News)" writes

Amendment accepted.

Reply to
Gordon H

Correct, (and dangerous).

When I was having driving practice in my uncle's 1936 Morris 10/4 it had a freewheel, and coasted whenever you lifted off the gas/accelerator/loud pedal...

Reply to
Gordon H

"Mrcheerful" wrote

^ Seems unlikely (unless it is a legacy of very early cars, that nobody has ever bothered to rescind). What's the punishment?

Reply to
DavidR

and what about hybrid or pure electric?

Reply to
Mrcheerful

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