How much more fuel will you use by driving at 70 mph, compared with driving at 50 mph?

Your vehicle will use less fuel if you avoid heavy acceleration. The higher the engine revs, the more fuel you’ll use. Using the same gear, and covering the same distance, a vehicle travelling at 70 mph will use about 15% more fuel than it would at 50 mph. However, don’t travel so slowly that you inconvenience or endanger other road users.