Gas tax is paid at the pump per gallon of gasoline.
FED is raising CAFE standards for all vehicles. Higher MPG means less gas consumed, but same number of vehicles are on the roads every day. Less gas purchased means less $$ available to fix or build roads.
And no, the contractors aren't building the roads with cheaper materials. All State DOT's have to follow Federal Highway Administration (FHWA) regs and issue standard specifications for all state work on state highways and federal interstates.
Local municipalities typically use DOT standards for their road construction also.
Problem is, we don't build our roads to last 50 years. We build them to last 20 years and then don't have money to rebuild them for 40 years...
