alex282 Posted July 11, 2013 Report Share Posted July 11, 2013 When I'm going down a hill or need to stop with no one behind me, I've started to coast more often by going in neutral to gradually come to a stop to try and save fuel and the brake pads but haven't really noticed any changes in fuel consumption I've read in some places on the internet that coasting actually uses more fuel than keeping the car in gear because more modern cars have a fuel cut off or something? Can anyone clear this up, for a gen 7 more specifically Link to comment Share on other sites More sharing options...
simonwref Posted July 11, 2013 Report Share Posted July 11, 2013 (edited) Yes. Google "hyperdriving". Boring though! Edited July 11, 2013 by simonwref Link to comment Share on other sites More sharing options...
Bill T Posted July 11, 2013 Report Share Posted July 11, 2013 On my old 318 if I coasted down hill in neutral the fuel consumption indicator went up, in gear with no or little throttle it dropped like a stone. I put it down to gravity turning over the engine rather than my petrol Link to comment Share on other sites More sharing options...
dublet Posted July 11, 2013 Report Share Posted July 11, 2013 http://www.popularmechanics.com/cars/alternative-fuel/news/coasting-in-neutral-fuel-economy 1 Link to comment Share on other sites More sharing options...
kishan38 Posted July 11, 2013 Report Share Posted July 11, 2013 In the theory test, I'm sure it says it increases consumption. Link to comment Share on other sites More sharing options...
simonwref Posted July 11, 2013 Report Share Posted July 11, 2013 Ok, I stand corrected. Link to comment Share on other sites More sharing options...
ams Posted July 11, 2013 Report Share Posted July 11, 2013 Uses more fuel, as your having to use petrol to turn the engine, when it's in gear the engine is being turned automatically and doesn't need fuel. Only way you could do would be to cut the engine but then youd loose brakes after the first use and you could get your self in trouble if you needed to move quickly Link to comment Share on other sites More sharing options...
Chris H72 Posted July 11, 2013 Report Share Posted July 11, 2013 I'd say it's a bad idea as you lose engine breaking and are not properly in control. In my mind it would cause the brake pads to wear faster because they are doing 100% of the work. Link to comment Share on other sites More sharing options...
alex282 Posted July 11, 2013 Author Report Share Posted July 11, 2013 Thanks for clearing it up, I always thought it used more fuel in gear because you can feel the car slowing down more and the rpm is higher but it turns out it uses less fuel to stay in gear Link to comment Share on other sites More sharing options...
Dorris Posted July 13, 2013 Report Share Posted July 13, 2013 (edited) Its all to do with how the fuel injection works, the ECU takes information from array of sensors from around the car two of them being throttle position and gear box so if you knock it in to neutral or push the clutch in and then coast down hill with the engine still running, the ECU is being told the engine is sat stationary so there for its on tick over and still supplying fuel to keep the engine running. If you are travelling down hill in gear and completely off the peddle with the weight of the car pushing you along then the ECU puts zero fuel into the injectors to give you engine braking, the reason the rev counter shows a reading in this situation is purely the speed of the gear box driving then engine. The other option is to turn the engine off but this really isn’t advisable as with the engine off you loose power steering and vacuum for the brake servo. These rules only applies to fuel injected petrol engines, CI and carburettor engines play by different rules of automotive engineering. Dorris Edited July 13, 2013 by Dorris Link to comment Share on other sites More sharing options...
mjc68 Posted July 13, 2013 Report Share Posted July 13, 2013 If you slow down using the gearbox (slowdown but stay in gear) you save fuel. All reasonably modern engines use no petrol while you slow down like this. If you have a car with constant fuel consumption display you can see this happen. My vectra (sorry for swearing) shows 999mpg when slowing in gear. Link to comment Share on other sites More sharing options...
Ghoulie Posted July 17, 2013 Report Share Posted July 17, 2013 (edited) Isnt It also illegal??? although how the heck they can prove it Ive no idea Edited July 17, 2013 by Ghoulscout Link to comment Share on other sites More sharing options...
dublet Posted July 17, 2013 Report Share Posted July 17, 2013 Your lack of steering input and brakes used will probably be a hint. As well as the key in the "off" position as they drag your corpse from the wrecked, mangled remains of the car. Link to comment Share on other sites More sharing options...
Ghoulie Posted July 17, 2013 Report Share Posted July 17, 2013 Your lack of steering input and brakes used will probably be a hint. As well as the key in the "off" position as they drag your corpse from the wrecked, mangled remains of the car. Coasting, not turning engine off Link to comment Share on other sites More sharing options...
Kobir Posted July 28, 2013 Report Share Posted July 28, 2013 If you slow down in gear, wouldn't you be wearing your clutch out? Link to comment Share on other sites More sharing options...
Monkey Boy 1 Posted July 31, 2013 Report Share Posted July 31, 2013 If you slow down in gear, wouldn't you be wearing your clutch out? No,because you are in gear and the clutch is fully engaged - No slippage of clutch plates. The only way the clutch can wear out is when the flywheel and clutch friction plate are at different speeds, This happens in the moments your foot is on the clutch pedal going through the momentum of gear change. or while you are attempting burn-outs. Link to comment Share on other sites More sharing options...
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