Get out of the road business
The federal government subsidizes roads by adding income tax money to the highway fund since the gas taxes are insufficient. This causes the federal government to subsidize suburban sprawl and driving which naturally increases air pollution and discourages alternatives to driving. Since raising gas taxes is unlikely to happen we don't we propose getting the federal government out of the road business completely. Eliminate the gas tax along with federal highway subsidies. States have smaller budgets and less ability to borrow than the federal government so states can't endlessly subsidize roads. The states will figure out how to pay for roads, and it is likely to be gas taxes and tolls. If a state chooses to fully subsidize it's own roads it will not affect other states much. Liberals and conservatives could agree on this strategy, it eliminates federal taxes, increases state control, and in the end makes a fairer playing field between cars and other modes of transportation