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In the city Sport mode would get you worse fuel economy Posted by Caarma [Email]  (#592)  [Profile/Gallery]
(more from Caarma) on Fri, 13 Jan 2006 14:24:22
In Reply to: No decreased mileage in sport....., Mike Lynch  [Profile/Gallery]
, Fri, 13 Jan 2006 13:20:21
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In general, (and I have run powertrain simulations to prove this), the later you shift, and the higher you rev before shifting, the more fuel you use. I think there is a misconception that because engines are more efficient with more throttle, that using max throttle would get you the best fuel economy. This is not true. At higher throttles, it's more efficient but trying to produce more power. Asking for more power by stepping on it requires the engine to use more fuel (even though at higher efficiency) than using light throttle and asking it to accelerate you more slowly with less efficiency.
This is somewhat analogous but different... With our Detroit Diesel engines (max torque at very low rpm and flat for a while until it decreases at higher rpm), the acceleration performance degradation by shifting earlier is minimal but fuel savings is substantial. This is because shifting late gets you out of the torque/fuel sweet spot and you are needlessly spinning the engine. The next gear gets you back to that sweet spot.
posted by 12.47.8...
, Fri, 13 Jan 2006 13:20:21, Fri, 13 Jan 2006 14:24:22 <-- Viewing This Message, Fri, 13 Jan 2006 16:33:53, Fri, 13 Jan 2006 17:02:16
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