"Dave Plowman (News)" wrote in message
...


That average is made up of a mixture of moving and stopped. Not by
vehicles driving at a steady 10 mph. Reduce the speed when moving and the
average speed goes down.

That's not always true.
The managed motorways have demonstrated that you can keep traffic moving at
a slower speed and get farther in a given time than letting the idiots
accelerate and brake hard, repeatedly.