(T22) Which Is Better - Coasting In Neutral Or In Gear?

[Mariius]

I own 2001 T22 D4-D 2.0 estate and I was wondering, which saves more fuel: coasting while in neutral or coasting while in gear? According to trip computer (which is known to be quite optimistic), while coasting in neutral, it shows, lets say, about 0.8l/100km. If in gear, it would show (about) 1.5l/100km. So is trip computer wrong or is it not (do these engines still pump diesel while coasting in gear)?

[revband]

In gear because on a fuel injected car the fuel injection is totaly stopped and no fuel is used.

[Mariius]

In gear because on a fuel injected car the fuel injection is totaly stopped and no fuel is used.

But as I have heard, only in modern engines fuel injection is stopped if coasting.

[revband]

I would consider your car to be modern enough for this to be the case.

[Heidfirst]

it's an interesting question.

in neutral idling the engine requires fuel to run.

fully coasting in gear the engine shouldn't require any fuel to run (it's turned over by the transmission system connected to the wheels) but the car will lose kinetic energy faster due to the friction etc. inherent in that.

I suspect that ultimately any difference is minimal & that from a safety point of view you are better in gear.

[Cyker]

I would vote for in-gear; D4Ds will stop injecting fuel when coasting in-gear (I think you need to be above about 1000rpm) whereas coasting in neutral, the engine is still using fuel for the tickover, although it will coast for much longer in neutral. It's much more dangerous to coast in neutral tho', esp. if you hit a subtle gradient or need to stop suddenly.

[Airfan]

In gear because on a fuel injected car the fuel injection is totaly stopped and no fuel is used.

But as I have heard, only in modern engines fuel injection is stopped if coasting.

Anything post 80s is modern enough.

[JAPCAR]

According to trip computer (which is known to be quite optimistic), while coasting in neutral, it shows, lets say, about 0.8l/100km. If in gear, it would show (about) 1.5l/100km.

Neutral coasting 0.4- 0.8 l/100 (depends of speed) is normal but in gear should be 0.0 l/100 above 1000rpm. My car do it according to trip computer.