Put aside for the moment the question of pollution coming from motor vehicles, something that is not easy to do because they account for about 20 percent of all emissions. For the time being, let’s talk about how much we spend on gas and how the federal, state and local governments manipulate those costs.

Keep the gas tax low and it costs less to drive. That helps those with limited incomes and especially those in non-metropolitan areas, the ones that lack public transit, because it makes it easier to drive to work, to shop, to the doctor, just for fun.

But that comes with a hidden cost because the more vehicles on the road, the more the roads and other related infrastructure such as bridges deteriorate, the more highways become crowded, the more we need to repair what we have and build more.

For decades those who study the issue have made the suggestion that increasing the gas tax would be the most straightforward solution. You could reduce the impact on those with lower incomes by making adjustments in income tax rates. You could make any increase come with an ironclad guarantee that the extra money would go toward needed repairs and improvements, not just get diverted.

No matter how much sense that made, it still involved raising taxes and nobody wants to do that or be associated with it. So the infrastructure crumbles, engineers issue annual alarms and not much changes.

Now, the Trump administration has joined the debate from an odd angle. It wants to roll back the standards imposed under President Obama and let cars pollute more. If not, the administration warns, people would get such good gas mileage that they would drive more and because the higher standards would make cars more expensive, they would hold onto their vehicles longer, leaving more older and less safe cars on those crowded roads.

You won’t find any studies to back this up because there aren’t any. Roads have become safer in recent decades because cars with competitive prices have incorporated safety features. Accident and fatality rates have risen recently not because of variances in gas mileage or a lack of safety equipment. As anybody who has studied the issue knows, distracted driving is the cause.

So put aside any claim that the administration is looking out for safety on the roads. It wants to push back on any regulations that hint at putting environmental concerns over any others. And if it can wipe out another Obama rule, all the better.

Oh, there’s just one other thing. In February, President Trump told members of Congress that he would like to see a 25-cent increase in the federal fuel tax to help fund improvements and repairs to the nation’s infrastructure. There was some confusion in the administration about the link between the tax and the road building and we have not heard much about this since.

So the president is now on the record as being in favor of increasing the cost of driving in two ways, once with higher taxes and once by making sure that vehicles do not become more efficient.