How do you determine the most efficient speed to drive your car at on a motorway.

by Stuart at 2008-02-24 10:03:53 (Forum::Public::Transport)

I always used to believe it was 56mph. But how can this apply to all cars with different drive shaft and gearing ratios?

My Rover with a 1.8t engine is doing 2200 rpm at 55mph in 5th gear. Rising to about 3000 rpm at 75mph, and I imagine 3750 rpm at 90mph!

How do I work it out?

--
Stuart