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63 comments on Eco-Driving promoted by the European Commission

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jmygann on May 31, 2008 - 12:52am Permalink | Subthread | Parent | Comments top

35 mph may be the most efficient

http://drive55.org/

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Engineer-Poet on May 31, 2008 - 2:41am Permalink | Subthread | Parent | Comments top

35 is considerably less efficient than 43 in my car.  At 35, my transmission will only upshift to 4th and the engine is turning about 1700 RPM; at 43, I'm solidly in 5th and the engine turns around 1400 RPM, with far less friction.  The difference per the trip computer is about 45 MPG to ~60 MPG.

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dwcal on June 1, 2008 - 4:57am Permalink | Subthread | Parent | Comments top

Transmissions differ, but with automatics, the most efficient speed is the lowest speed at which the torque converter lockup clutch engages in top gear. 45-50 mph sounds about right.

With a manual, I've been short-shifting in city driving and it seems to give about a 5-10% improvement. City traffic is slow enough that the lack of acceleration doesn't matter. There are places where you need more acceleration, like to safely merge onto freeways, so use common sense here.

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indyphil on June 1, 2008 - 9:45pm Permalink | Subthread | Parent | Comments top

I think you are right, unfortunatly one of my vehicles is programmed only to "lockup" at 50mph. If I dont get over 50 it will NEVER lockup. Its possible to reprogramm the Transmission to lockup earlier and even short shift. I wish more cars would have transmission modes, like economy and sport. of course manual transmission cars dont have that problem...

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Petrus on June 3, 2008 - 10:44am Permalink | Subthread | Parent | Comments top

That's CORRECT !

I've driven many vehicles, trying eco-driving and the most efficient speeds are 47miles/hour (80km/hour) and ABOVE !

Ford Excort - Manual 5th gear does not work well below 40mi/h .
My Volvo switches to overdrive at 47.5mi/h.
My Chrysler Town&Country switches to overdrive at 46 mi/h. It has fuel calculator, that shows the most efficient speed at 62mi/h.

But if you drive at the limit, automatic thransmissio switches back and forth, using more energy. 50mi/h+ is the answer.

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63 comments on Eco-Driving promoted by the European Commission

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