Somebody else suggested taxing tires, but that would be hard as tires are obtainable out of state.
The underlying facts of road maintenance are that basically all of road maintenance (except that attributable to erosion of the roadbed) repairs damage caused by heavily-loaded trucks. Objectively, road damage goes exponentially with axle load. Cars' axle loading is so far below that of laden trucks as to to be wholly negligible. Thus, the justifiable taxation for road usage, if any, should fall on truck operators.
Car owners benefit from truck traffic about equally with non-owners, however many cars they have, but moreso if their income is higher. So, the legitimately defensible way to pay for roads is straight from the general fund.