How do you determine the most efficient speed to drive your car at on a motorway.
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?
If you'd like to post comments on this site, just register here