Coasting?

[raywong]

hi ppl

i saw someone said this in another forum,

'Neutral -> engine rotated by the fuel (idle)

any gear -> engine rotated by the force from the car'

the guy on that forum was saying that by coasting, u would actually use more fuel rather then savn fuel, and also do u guys think this is a dangerous thing to do?

thx

Ray

[alanbradley]

That's what I heard too...

I don't like coasting the car out of gear, I feel that you just don't have the control over the car that you should have.

As for the fuel saving, it will be so miniscule that you will hardly notice the difference, but I agree with the guy on the other forum - staying in gear will use less fuel in a modern car.

(I think what I've just written makes sense... )

Alan

[jaxx]

thats true

modern EFI engines cut the fuel when you coast in gear

but keep it ticking over if you go into neatral

[Karma Supra]

Might as well turn the engine off and roll if downa hill if you REALLY want to save fuel :P

Don't believe everything you read in forums mate

Even when rolling in gear the tick over amount of fuel will be injected in as the throttle is still in the idle position, and the ignition is still on!

Jaz just seen your post...

Surely that means that the mixture leans out???

[JustJJ]

As far as I know... it saves a little.. but not much.... also I have been told its dangerous because its difficult to control speed you tend to speed up / slow down a lot faster than you'd think on slopes plus brake bias on cars tends to take into account engine braking, take that away and if you brake hard you could end up locking the wheels that aren't normally driven. Not such a problem now as lots of cars have ABS... v bad in a front wheel drive car without it though.

:P

Not worth it really :P

[T V O R]

Coasting doesn’t save fuel...

Have to agree with you all on this, when you take it out of gear fuel is added to keep the car ticking over, leave it in gear and coast the last few yards to the junction/lights/to a stop for free!

It was also mentioned on Top Gear not so long ago

[Crisis]

Coasting is dangerous, your car is basically free wheeling. My dad used to go ape ***** cause i used to do it when going around corners when learning (dont ask why I dont know why i done it) although I reguallry when I see a red light up ahead pop it into neutral and roll up to the lights, but sometimes pop it into 1st ready to pull away with my foot on the clutch all the time...

I notice that last bit of popping it into first, leaving the clutch in while coming upto lights can't be done in all cars, alot of gearboxes dont like it for some reason. The IS200 is one of them!

[breezer]

i heard it consumes more petrol when you take it out of gear and just role!

[Kelvyn]

Jaxx is right, modern EFI systems cut off fuel when you let your foot off when in gear, you can sometimes feel when it cuts back in again as the engine approaches normal tick over speed.

In the old days when cars had a carburretor coasting would indeed save you money as less fuel was delivered to an idling engine than one slowing down. Not many of you will be old enough to remember, but some of the old Rover cars (when Rover meant quality) actually had a freewheel (like a bicycle) built into the transmission. Sold as an economy device it was like putting the car into neutral. The down side of course is that like automatics the brakes wore quicker, and of course in those days they were only drum brakes (even the fronts).

Coasting really isn't good practice, and as has been said wont save you money.

[daktari]

Not only is coasting actually not fuel efficient and dangerous it`s actually illegal! Proper control and all that malarky. Pretty much the same as eating an Apple in the eyes of plod. :P

[Blue84]

I never coast - the gears are there for a reason so I use them!

[raywong]

thx for the advice... i dont always coast, but as crisis said i sometimes use it when the cars approaches roundabouts and traffic lights and i know the car is fast enough to roll there, i just wonder if it saves any fuel... thats all, but would probably stop doing it now.

Thx

Ray

[Boro Sera]

on the other side of the coin though, There is an annual event to build vehicles that will travel as far as possible on a litre of petrol. The current record for this is approaching 2500km/l IIRC.

The preferred techniwue of the competitors is the 'Coast and Burn' method, whereby the speed is built up i.e. BURN, then the vehicle freewheels with the engine idle i.e. COAST.

Must point out that this is on a track in specially designed cars though, and wouldn't work in a standard car, and isn't safe or legal to do anyway. ( before you all start ! )

Rich

[Leeky]

Oh dear, you lot all worrying about a tiny bit of fuel being saved. Drive a Supra for a weekend

[houston]

petrol prices aint that bad, if your greedy enough to try and save by coastin then you should try walking!

also easier for car to cut out when coasting, not a nice situation when your power steerin turns off and u realsie just how hard it is to turn without it

[cfc1]

petrol prices aint that bad, ......

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Where do you live again??. Is it in the UK??.

the price of petrol is WAY too expensive :arrgg-matey: .. its because of these over inflated prices that the cost of living is so expensive!!.

lol sorry.. this could be a full topic on it's own.... lets get back to the thread.

[houston]

i know what u mean about sky high petrol but if it ever came to the point that i was coastin to save it then i'd start to think im in the wrong car! not that i wouldnt mind cheaper petrol.

[sotal]

I had this arguement once before. It turned out that coasting out of gear does use more fuel than coasting in gear....

but if you coast down a hill out of gear you will accelerate with using little fuel, wheras coasting in gear will decelerate due to engine braking and slow you down more - You will then need to use more fuel to get the speed back up.

So you do actually save fuel by coasting out of gear

(problem is when you get to the bottom of the hill, accelerating down the hill and roll it on the bend!! )

[Karma Supra]

Oh dear, you lot all worrying about a tiny bit of fuel being saved. Drive a Supra for a weekend   

←

Pah!!! yours is efficiant compared to some!!!!

[Crisis]

I remeber in 2000 used to be 65p per litre. It went upto around 86p per litre but its down to around 77p per litre at the moment.

Read in Auto Express the chances of things happening this year in the car world. £1/ltr was 8 to 1. Flying cars on production to the public was 250 to 1. 80mph limit on the motorway was only like 3 to 1 or something.

[Fmrl]

If you buy petrol when it's colder then you get more for your money coz it's denser.

[Crisis]

Yep thats true. Do it early mornings.

[Karma Supra]

its when you fill up... go in to pay... buy addative/injector cleaner, whatever.. come out... open the fuel tank and all the fuel comes out where its expanded in the warmer tank :o :ffs:

[dazwan]

All this worrying about saving a few pence!

Just go out and get a little 125cc Motorbike. Some bikes do over 100mpg! and to really rub your noses in it, the road tax on a 125 was £15 a year the last tiem I looked!

I really need to get a bike!

[mrrandom]

obv is true, while coasting ur not reving your car are u? so why wud it burn fuel?