US PIRG has a new report, asking Do Roads Pay For Themselves? (and answering: "Setting the Record Straight on Transportation Funding")
As with most advocacy work, most of the facts are correct, the issue is in the spin. It is well known that "roads" do not pay for themselves, most local streets and roads are paid for from general taxes (esp. property taxes) and most roads are local (and most travel is local). The question is really 'do "highways" pay for themselves?', which the answer is much more difficult. Unfortunately the authors loosely interchange the terms "highways" and "roads" to suit convenience. They are different, they serve different purposes, and they are funded differently. If cars suddenly vanished, we would still need roads, just as we had roads before the advent of the automobile. They might be narrower, there might not be highways, but there will always be roads.
The authors have a heterodox history of the gas tax (but seem to emphasize the federal over the state, which is a common fallacy in all national transportation discussions, promoted by those based in Washington. If the federal government's role in transportation funding disappeared, it would take years to really notice out here in the country, since DC funds new projects, which would just stop being built, resulting in no change to existing infrastructure.)
The authors have an interesting take on the term 'user fee', suggesting that gas taxes aren't really user fees because (a) they were sometimes used for deficit reduction, (b) they are shared with other surface transportation (transit), and (c) they don't correspond with use. While I don't like either diversion, that doesn't mean that gas taxes aren't user fees, just that Congress can't avoid meddling. Just because gas taxes imperfectly measure use (i.e. it is proportionate to gasoline consumption instead of miles, it is assessed on travel on all facilities, not just highways), doesn't mean it is not highly correlated. It is a surrogate, as are most fees. They are charged only to users of motor vehicles (admittedly only those users who use fuel, but that is approximately all users at this stage of technology). It would be better if user fees (preferably tolls if transactions costs could be reduced, but gas taxes in the interim) covered all costs of operating and maintaining existing streets, roads and highways, so we could depoliticize the issue, and treat it like the public utility it is. It would be better if the charge could vary by location and time of day, it will eventually do so.
User fees as the primarily source of funding is certainly economically feasible (i.e. we could raise the gas tax and cover all the costs if we so chose in the US), but politically we are not there yet, as politicians still have a fear of being unelected.
Financing new roads and highways is a separate problem from maintaining the existing. They should not be conflated.