The book ("Sustainable Energy - without the hot air") in http://tech.slashdot.org/submission/1030811/Solving-the-Energy-Crisis-by-Tripling-Electricity describes an interesting variant on this.
Instead of charging by distance travelled, the idea is the charge by the level of congestion, which is measured by a radio transmitter/receiver which detects the proximity of other (similarly equipped) vehicles. Congested driving leads to higher fuel consumption, so congestion charging taxes both high fuel consumption and impact on other road users.
Slashdot Mirror
The book ("Sustainable Energy - without the hot air") in http://tech.slashdot.org/submission/1030811/Solving-the-Energy-Crisis-by-Tripling-Electricity describes an interesting variant on this. Instead of charging by distance travelled, the idea is the charge by the level of congestion, which is measured by a radio transmitter/receiver which detects the proximity of other (similarly equipped) vehicles. Congested driving leads to higher fuel consumption, so congestion charging taxes both high fuel consumption and impact on other road users.