Gas tax revenues are generally only used for capital projects, not operating expenses. The cost of plowing or resurfacing a road is normally paid out of general tax revenues.
In every state in the Union, the state gasoline tax pays a bit less than half the cost of building and maintaining state highways. Other car-related taxes and contributions from the general fund (sales taxes and income taxes) make up the remainder.
Automobile drivers are heavily subsidized by the taxpayers in their respective states. It's one of the dirty little secrets of the transportation game.
When you have a chance, check the budget line for your town, township, and county for streets and roads, then check the gas tax they are collecting. You'll find it is tens of millions annually, and the gas tax collection is nil.
If we relied on gas taxes only to pay for roads at the current level of taxation, we'd never be able to leave our driveway, since there'd be no local road system.
You'd be surprised how much of your state general revenue taxes and your local property taxes are going to subsidize automobile travel.