Quote:
Originally Posted by Quacker
I believe that coasting in Eco mode is likely to actually use more fuel than when on the over-run with gears engaged in other modes. Not much but certainly not more economical.
Logically, when a modern petrol and Diesel engines are on the over-run, compression braking, no fuel whatsoever is injected. However when coasting, the engine must inject fuel to maintain idle speed, otherwise the engine would stop.
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Hi Quacker, old thread but new to me.
Your statement above is correct for the BMW M47 2 litre engine and the Honda 2.2 diesel, but not so for the 1969cc Volvo D4.
On the over-run say in 4th gear the engine never runs below 1000 revs and therefore engine braking is reduced often resulting in having to use the brakes when in other diesel cars the engine brake would have been sufficient. If the clutch is disengaged at this point the revs drop to idle about 850 revs.
I asked "Clan" about this and he replied that it was done deliberately to protect the dual mass flywheel from drivers who use too few revs and causing transmission judder.
Personally I would prefer the old system and drive in sympathy with the car.
Cheers, Pete.