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Old 11-03-2012, 12:48 PM   #4 (permalink)
Arragonis
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Quote:
Originally Posted by wungun View Post
From what I understand, Almost all modern car engines shut off the injectors when the engine is down revving, foot off the gas in gear.
As mr M says this has been covered - the simple answer is "it depends". Firstly are you looking to maintain as much momentum as possible to coast as long as you can (on the flat) - in which case out of gear wins. Or are you going downhill or slowing to a stop then if your ECU cuts off the injectors in gear wins.

If your car can handle it, and it is legal where you are and you are in full control engine-off wins - the Prius turns the engine off when it can.

You also need to know your car - for example in my Aygo it won't go into fuel shut off mode unless the engine rpm is over ~1400. In a low gear this results in a lot of engine braking, in a high gear less.

So as I tapped it depends - on the scenario, your car and what you feel comfortable with.

Quote:
Originally Posted by Flakbadger View Post
My car at 40 MPH, in neutral: ~245 MPG
My car at 40 MPH, engine braking (3rd gear) ~130 MPG

Conclusion: The Toyota Yaris manual transmission DOES NOT DFCO. Approximately twice as many MPG's in neutral.
Does yours have the same rule as mine - i.e. > 1400 rpm ? These results could be due to the fuel required to maintain idle (~900 rpm) out of gear vs what the ECU thinks is needed at whatever rpm in 3rd at 40 MPH is - I would google this last factor but your US Yaris might be different from our UK one.
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