Was at a friends house for a BBQ tonight and found his copy of Motor magazine and read this article. Check it out.

http://www.motor.com/MAGAZINE/Pdf/072007_09.pdf

Wow, good read. Thanks for posting it.

According to this article, best fuel economy may be found at a moderate rpm, rather than the lowest possible.
40-45% of the rpm range is what is suggested... next time I go on a road trip Im going to try this.
On the V6, 2600-2950 rpm should equate to around 70-75mph IIRC.

This post has been edited by dogstar: Jul 22 2007, 04:58 PM

You have to be careful. The most efficient engine operating speed can conflict with drag, rolling resistance, and other frictional losses. For example, there is a very serious increase in wind drag going from 55mph to 75mph. To get the most efficient driving speed, one may have run the engine a tad below the most efficient RPM.

Another interesting thought is that by using that 40-45% guideline, it may be necessary to cruise in 4th gear at ~55mph.

Anyway, good article. I'll be looking for more on that site.

Isn't it interesting that they still claim 55mph to be the most efficient speed for gas mileage? After all this has been claimed since some 3 decades ago... Would you expect new engine technology to CHANGE that "sweet spot" to a higher speed?

I think that engine and transmission technology, combined with aerodynamics have changed the sweet spot, but I think for sake of argument they used the double nickel to prove that it wasnt just a random number but chosen to coincide with increased efficiency.

I understand that wind resistance changes, but all other things being equal, I dont believe that rolling resistance is a variable factor after a certain speed.

Frictional losses were discussed in that article, and combined with pumping losses they were described as the reason that 40-45% was the best range.

Dog,
You're welcome. I thought others would enjoy learning about this technology like I was.

BTW hatter where did you move this to?