Re: How do you determine the most efficient speed to drive your car at on a motorway.
My car, a diesel Golf Plus, has a fuel consumption display, both current mpg and journey mpg. On motorways, 50-60mph is the most efficient, with the mpg going down steeply over 70 mph. Constant speed, by using the cruise control is not the most efficient, slowing down slightly when going up hill and speeding up when going down is more economical for a given average speed. The resistance, both rolling and wind increase expodentially with increasing speed.
If you'd like to post comments on this site, just register here