Fuel efficiency at motorway speeds...

[meathead]

Am I better off in regard to fuel economy cruising on a motorway at 60, 70, or 80 mph?

Not concerned (yet!) with tyre wear, just fuel consumption. Does anyone have the figures to back up a specific speed.

[herby0001]

No figures as such, but official fuel consumption figures quote the extra urban (motorway, I think this is!) driving speed to be 100km/h or 56 mp/h. That's probably pretty economical, as the faster you go, wind resistance becomes more significant. Do a tank full of fuel at 80mp/h (approx 500 miles) and a tank of fuel at 60mp/h (approx 600 miles) - the difference is significant - all dependant on your driving style though, such as acceleration and braking.