The rules are simple - the car which uses the least fuel over the set route win.

In the event of a tie the greater number of correct observations will determine the winner/s.

There are two classes only - red cars, and cars which are not red - I think that's right?

Or maybe it's for cars less than two litres, and cars above two litres.

Note - the rules for 2011 involved the weight of the car to make the competition more even, so the calculations were based on l/100 km/tonne.