In 1994, a passenger car averaged 20.7 miles per gallon (MPG) and drivers paid 3.2 cents in state and federal tax per VMT. Tax revenues per vehicle mile traveled (VMT) are decreasing in real terms while expenditures are increasing in real terms.The tax also aims to counter the negative side effects caused by driving petroleum-burning motor vehicles and their contribution to congestion. The motor fuel tax is a relatively well-designed tax which acts as a user fee by raising revenue to fund the highway system.While many states have increased motor fuel tax rates over the last decade, the federal government has not updated the gas tax since 1993. The future of funding for America’s highways has been the topic of much political discussion for decades.