President Trump recently proposed a 25 cent per gallon increase in the federal gasoline tax to pay for his infrastructure spending proposal. In a recent report, the General Contractors Association of New York argues that such an increase could be a win-win for motorists. In all but one state, drivers would save more on vehicle repairs tied to poor road quality than the tax hike will cost them. In all but seven, crumbling roads already cost us more than double what the higher gas taxes would.

The cost of improved roads and highways might very well be less than what most motorists spend on related auto repair bills. Nevertheless, there are better ways to raise enough money for better highway maintenance.

First, it is worth pointing out that the aforementioned analysis is based on some questionable assumptions. We could not count on states spending all (or even most) of a gas tax increase in a way that would actually reduce road damage to vehicles. All kinds of interest groups would like to get their hands on that money. And even if it were all earmarked for transportation projects, it could be spent in a variety of ways. A substantial share would likely go to public transit agencies that usually claim close to 20 percent of highway trust fund money. Quite a bit would likely go toward building new highways, and not necessarily just in congested areas where the need is the most urgent.

Furthermore, while a large portion of the extra funds may help reduce damage to vehicles, much of the wear and tear on our cars and trucks comes from local streets and roads. These are maintained by local governments. We could earmark more federal money for this purpose, but don’t count on that happening. The larger question is whether it makes sense to continue to rely on fuel taxes to fund our highways. More and more Americans are buying vehicles powered by electricity or hybrids that use very little gasoline. They pay much less than their share of the costs of highway construction and maintenance. The gasoline tax will eventually become outdated as the amount of gas we buy falls over time.

If we want a sustainable plan to better fund highways, we should consider replacing the gas tax with mileage-based user fees (MBUFs). With fuel taxes, drivers pay the same amount whether they are driving on a congested freeway or a little-used rural road. Heavy trucks do not pay enough to cover the disproportionate cost of the damage they cause to highway surfaces and bridges.

With MBUFs, the price each vehicle pays per mile can vary to account for damage caused by different types of vehicles. They can also address congestion and related costs with rates that vary based on time of day and the location of each highway.

MBUFs have been successfully pilot tested in several states. They require a method for recording miles traveled by each vehicle and a way to securely and privately communicate the information to a firm or government agency, which then calculates a bill. Devices inside vehicles record miles and the location of those miles. They can be administered by state governments or by private firms permitted to own or manage roads and highways.

Admittedly, it would take quite a few years to implement a system of MBUFs. In the interim, federal fuel tax increases could provide revenue to improve highway maintenance. A better approach, though, would be to reduce federal spending and let states and local governments pay a bigger share of the costs of building and maintaining streets, roads, and highways. State and local governments are more likely to prioritize their spending in a way that is consistent with the interests of motorists, particularly if it is funded by fuel taxes.

The quality of highway maintenance and the need for additional spending varies considerably from state to state. Some states, such as Alabama, do a better job than others with existing revenue sources. Those states need not raise their fuel tax rates much, if at all. Other states have not been spending enough, and have experienced substantial deterioration in the quality of their pavement and bridges. It makes sense for drivers in those states to pay higher fuel taxes until a system of MBUFs could be implemented.

Tracy C. Miller is a senior policy research editor with the Mercatus Center at George Mason University and the author of several transportation studies.