What is greener than a VMT tax? The case for an indexed energy user fee to finance us surface transportation

Charging highway users per mile has been proposed as a replacement for the US motor fuel tax. A miles traveled user fee, however, does not encourage energy efficiency in vehicle design, purchase and operation, as would a user fee levied on all forms of commercial energy used for transportation and indexed to the average efficiency of vehicles on the road. An indexed roadway user toll on energy would induce two to four times as much reduction in greenhouse gas emissions and petroleum use as a pure mileage fee. However, it is not a substitute for pricing greenhouse gas emissions and would make only a small but useful contribution to reducing petroleum dependence. An indexed energy user fee cannot adequately address the problems of traffic congestion and heavy vehicle cost responsibility but it could be a component of a system of financing surface transportation that would eventually also include time and place specific monitoring of miles traveled for congestion pricing, externality charges and heavy vehicle user fees.