I managed 7.2 miles last night in neutral.
(And if you want to wittter on about that being naughty, then bog off.)
I'm very tight and I normally turn off my engine at the top of Burrington Combe and freewheel all the way to the bottom. Probably only a mile though...
Impressive!
I thought I was doing well at 3 miles exactly. (Devauden to Howick, if anyone knows it...)
Genuine question - doesn't turning the ignition off (as per edd's post) mean the power steering (and poss. brake servo?) won't work? Not that it makes much difference to me in nice flat Cambridgeshire...
3 miles, most nights.
Cox tor car park down into tavistock centre.
coast over the top of the hill and can hit 70 ish
I wish you hadn't posted that Kenny.
I love a challenge and that's an impressive benchmark. I'm thinking where I can aim for a PB. 7.2 miles, where did you do that?
Hate doing this.... On a boring safety note, in my car the engine needs to be running for me to have power assisted steering and braking, so neutral it is for me. Different cars are available and may vary!
edit: McGreedy already beat me to making the old man health and safety comment.
MrGreedy - you're correct about the brake servo. I normally have to restart half way and then turn the engine off again.
(And if you want to wittter on about that being naughty, then bog off.)
That'll reduce the number of posts on this thread by 99%.
I've only ever coasted about a mile, down the hill from my house.
Probably saves a thimble of petrol each time.
By the year 2060 I will have saved a whole tank of petrol, by which time there will be no oil left anyway, so saving a little bit here and there is pretty pointless seeing as it's going to run out anyway at some point.
I should probably spend more effort finding ways to not need a petrol engine.
Doesn't coasting in neutral use fuel so that the engine keeps turning whereas coasting in gear will use the kinetic energy of the car to turn the engine over and result in no fuel being used?
Doesn't coasting in neutral use fuel so that the engine keeps turning whereas coasting in gear will use the kinetic energy of the car to turn the engine over and result in no fuel being used?
The guy running a speed awareness course I did recently was saying something along those lines.
17.8 miles.
Although that was down towards Death Valley in Colorado. Does that count?
In this country? No idea at all - but the challnge starts now. Where was 7 miles?
Ditto on the turning the ignition off, I'd have no steering or brakes, and powerd ones are a bugger to operarte without power going to them!
from a fuel efficency POV its better to get up into your top gear and coast, rather than put it in neutral
wouldn't it being in gear slow it down?
Yes, Fuel is saved by coasting in a high gear, although this may be offset by slowing down faster. Right, done that.
Yes, some cars will lose all power steering and brakes, although others never had them to start with (I remeber a 1970's transit my father used to own, I'm not sure even the engine was 'power' in that!)
Right, back to the challange! I'm now going to find out how far I can coast through Weston Super Mare traffic on a Tuesday lunchtime...
wouldn't it being in gear slow it down?
not nec in top, depends how steep the hill is
My understanding is that in a fuel injected car in gear is more fuel efficient than neutral.
However, this was simply to see how far I could roll for in neutral (engine was on for steering though).
It was on the A82 in Glencoe, starting on the long straight just north of Alltnafeadh (the Devils Staircase) and I made it to somewhere between the NTS centre and Glencoe village. The crux is by the back road near the Clachaig Inn.
It would slow it down a tad, even in top, but tickling the accelerator even all the way down would not use more than coasting. As the revs approach idle you should change down as the engine will start fueling to avoid stalling.
not in top
In my extensive experiments to save fuel on motorways I've always found that coasting in top gear slows me down too much. Even on big downhills like the M62.
The best fuel saving option I've found is to sit 20m behind a lorry at 56 mph. I once managed 89mpg in my Focus 1.6 estate doing this between Oxfordshire and Manchester. Bloody boring though. Every now and again I'd change lorries for a different view.
I always used to wonder why old Saabs have a freewheel flywheel until I watched Top Gear the other night and they explained that 2-stroke engines will be starved of oil if they are used for engine braking over a significant distance.
A friend tried this when steering locks started to become common on cars. Tried coasting with the ignition turned off and crashed on the first bend. 😕
A long time ago I stayed in a farmhouse that had a private road to it. The road turned left and dipped down sharply into a little valley and then up the other side to the house.Just before the end of the downhill bit there was a sharp left kink.
I used gather as much speed in my Mini Pick-up as possible and put it in neutral at the top of the hill then see how far I could coast down the hill, round the kink and up the other side. This depended on having the nerve to leave the brakes alone on the steep dip and the bend. I got faster and further each time which involved a higher entry speed and subsequently higher corner speed at the kink. Eventually,I was only a few yards shy of cresting the rise to the house.
The record effort took place on a dark, windy night. I carried even more speed than normal, plunged down the drop and steadfastly kept off the brakes into the kink. Here, the 6x10s ran out of grip (or I ran out of talent)and the Mini flew off into the ditch, flipping onto its side.
What was the question again?
Steering should only lock when the keys are removed, you can turn the ignition off and leave the keys in and the steering should still work.
Doesn't coasting in neutral use fuel so that the engine keeps turning whereas coasting in gear will use the kinetic energy of the car to turn the engine over and result in no fuel being used?
1. The amount of fuel going in to the engine at idle has to be enough to overcome the friction at ~1000 rpm, with an additional factor to avoid stalling.
2. If you coast in gear, you have the friction caused by the enginer being turned at ~2-3000 rpm.
Does the throttle stop feeding the fuel required to idle the engine, just because you're in gear and coasting?
Your mechanical losses are greater in gear as you're turning the engine more quickly. Do you burn less fuel? Which is the greater effect?
Does the throttle stop feeding the fuel required to idle the engine, just because you're in gear and coasting?
Yes, mine cuts off fuel supply to the engine when in gear and coasting.
all these posts assume you do it to save fuel.
I do it just to see if I can, there is a set of corners in the middle you have to carry enough speed through to get over the long flat section before the last drop into town.
Funnily enough, it was much easier in my wifes old 106 with skinny 145 tyres on, rather than my A3 with 225's
Have never coasted anywhere. Am either accelerating or on the brakes
Surfmatt?
not in the same league 🙂
Looking out of the window here, I estimate I freewheel about 80m, from the turning off the main road to the space on my drive. I have to get the braking right as I have to bump up the kerb, so need enough KE to do that, then quickly brake as the drive is downhill, before hitting the garage.
That's pretty good for Fenland.
Probably best
About five miles from the top of the Goulin to "big bridge" near Durness. Can't think of anywhere else I would want to try it TBH.
Keep it in gear a Modern engine will put no fuel at all when coasting in gear. where in neutral it will obviously have to use some to keep it all spinning round at 1000RPM
Well, it's official, even hitting 90 past the police station, I still only coasted 50yards before another blue rinse old biddy pulled out in front on me in her bloody micra.
Had to brake so hard I spilt the coke I was drinking and there were fries all over the floor.
So, it's 50yards max in W-S-M lunchtime traffic.
Mt Teide to Los Gigantes, Tenerife. Several times in the dead of night.
16 miles, 100 yards of power and another 7 miles.
Hot, smelly brakes!
Must be good on a bike, not sure about the ride up, though it is morbidly attractive 😉
Cheers
Paul
i love this and have lain awake at night thinking how to prove it.. we live near cragg vale ( longest continuos slope in uk about 5.5 miles) so its simples to coast from the top to mythmroyd 6 miles at a push. difficult to measure the fuel useage though.. but not on my motorbike. with the fuel turned off i have just the float bowl ( about an egg cup) on tickover the bike will go top to bottom but in 4th gear shes dry within a mile so i can state catagoricallythat on a 1963 francis barnett model 92 its cheaper coasting out of ger than it is in gear..
How far is the descent off either side of Shap on the M6?
I once did 7 miles without touching the controls. Long straight uncambered desert road in Arizona on cruise control. Could have got in the back and had a picnic. I didn't obviously, that would be silly.
*ponders Glenshee down to Braemar
coasting from level 5 to ground exit in my local multi-storey carpark is about a fun as it gets round here.
gotta keep the nerve to stay off the brakes at the tight turns into the ramps, avoiding swiping off the front wing of those badly parked 4x4s..... 😛
How far is the descent off either side of Shap on the M6?
Mmmm, good call, I go that way a few times a year.
Does the throttle stop feeding the fuel required to idle the engine, just because you're in gear and coasting?Your mechanical losses are greater in gear as you're turning the engine more quickly. Do you burn less fuel? Which is the greater effect?
When on overrun (in gear, but no pedal), a modern engine will inject zero fuel and use the flywheel effect of the engine to keep it turning. Only once the engine approaches idle speed will the idle governor kick in and start putting fuel in. You would use much less fuel by 'coasting' in gear, accelerating gently when starting to slow down a bit and then coasting in gear again than you would be cutting the engine and starting it if you need power steering! Not to mention that losing power steering, brake servo etc is not the most sensible idea....
dazh - In my extensive experiments to save fuel on motorways I've always found that coasting in top gear slows me down too much. Even on big downhills like the M62.The best fuel saving option I've found is to sit 20m behind a lorry at 56 mph. I once managed 89mpg in my Focus 1.6 estate doing this between Oxfordshire and Manchester. Bloody boring though. Every now and again I'd change lorries for a different view.
I think I'll be trying that soon. Although at 56mph fuel economy would be pretty good anyway in my 307SW, get around 50mpg normally.
Not huge distances but the A68 from the border signpost (towards England) is a good one. Not as much fun as trying to coast up and down the blind crests a few miles later 😀
I sit in the slow lane on the motorway till a coach overtakes and get a 'tow' until either he or I turn off (they do 70mph unlike lorries 😀 )
Ran out of petrol going from deep springs to big pine, so we coasted down Ott of the mountains. It was ten miles or so.
ahh whispering sixth as it used to be known, maybe should be seventh now. Do it as much as possible to eeek out the diesel.
I sit in the slow lane on the motorway till a coach overtakes and get a 'tow' until either he or I turn off (they do 70mph unlike lorries )
Yeah coaches are better, but you have to drive closer to compensate for the higher speed. This also has an added dimension as usually there are other drivers doing the same, and you end up competing with them for the spot behind the coach. My tactic in this scenario is to try to anticipate when the coach will need to change lanes, then draw alongside the car behind and let the coach in with a flash of the lights. 🙂
Drafting is a great fuel saver but conflicts somewhat with the "Only a fool ignores the two second rule" idea.
How far from Glenshee Ski Centre to Braemar? Must be around 5-6 miles?
I don't think you can coast from Glenshee to Braemar, as there is an uphill section about 1-2 miles from Braemar.