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Old 11-05-2015, 05:53 AM   #43 (permalink)
Angib
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Join Date: Dec 2008
Location: England
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It is amazing how many people think that pressing the accelerator pedal less means higher fuel economy.

If you need energy, for example to reach your chosen cruising speed, then you should buy it on the best terms possible, when the engine is operating as near peak efficiency as possible. As the graph shown a long way above demonstrates, a petrol/gas engine is nowhere near peak fuel efficiency with the throttle nearly shut, whatever the revs. So the most fuel-efficient acceleration is with the throttle wide open at revs up to about peak torque. I was a kid when BMW confirmed this by measurements in real-world vehicles.

Another tip is don't get a Scanguage, as you can end up minimising current fuel economy which may increase trip fuel economy for exactly the same reason.

Ultimate (closed track) fuel efficiency competitors never operate a petrol/gas engine at part throttle openings: they use 'coast and burn', accelerating at maximum throttle up to a (low) maximum speed and then coasting with engine off until they have slowed to the minimum speed that will enable them to achieve the minimum average speed for the competition. And if they can get over 1000mpg (yes, 1000, not 100) from their specially-built competition vehicles, this behaviour is not because they don't know how to drive economically.

Acceleration is like removing a Band-Aid - all kids start out thinking it will hurt less to peel it off slowly, but all adults have learnt that minimising the duration of the pain is better.

As renault_megane suggests, the picture is nowhere near as clear with diesel engines, as they have reasonable part-load fuel efficiency.
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