Tim Haab on the question of which is better, a fuel consumption-based or mileage-based motoring tax:

The answer comes down to one simple question:  What is the goal?  If the goal is revenue generation then a mileage tax makes sense.  If the goal is fuel efficiency then a gas tax makes sense.  If the goal is revenue generation and improved fuel efficiency, then a graduated mileage tax may make sense.

Insert appropriate comment about walking and chewing gum while cooking dinner in the shower.