This is a great argument for why a price on carbon is a better solution than a direct regulatory approach. You can't game the price at the pump or find a loophole, or at least its more difficult to do so.
(Yes, it's not a perfect policy, but please don't criticize it with an argument equivalent to saying that a unit of pollution is infinitely bad. It's not.)
Example: I bought a used 2012 Prius in 2015. The moment that car was built an extra 50 tons of CO2 was slated to be emitted over the next 15 years. You can raise the gas tax as much as politically possible and that won't change the amount of CO2 the car will emit.
> In the final hours of Scott Pruitt’s tenure as administrator, the Environmental Protection Agency moved on Friday to effectively grant a loophole that will allow a major increase in the manufacturing of a diesel freight truck that produces as much as 55 times the air pollution as trucks that have modern emissions controls.
> The move by the E.P.A. came after intense lobbying by a small set of manufacturers that sell glider trucks, which use old engines built before new technologies significantly reduced emissions of particulates and nitrogen oxide that are blamed for asthma, lung cancer and other ailments. …
> But agency officials confirmed to The New York Times that, through the end of 2019, the E.P.A. will not enforce an annual cap of 300 gliders per manufacturer that had been imposed in January. …
> An estimated 10,000 glider trucks were sold nationally in 2015 — about 4 percent of new heavy-duty truck sales — and production could soon return to that level. … The agency, she said, is also considering formally delaying the 300-unit cap until December 2019 — by which point it hopes to have permanently repealed the cap.
[1] "‘Super Polluting’ Trucks Receive Loophole on Pruitt’s Last Day" (July 6, 2018) https://www.nytimes.com/2018/07/06/us/glider-trucks-loophole...
[2] "How $225,000 Can Help Secure a Pollution Loophole at Trump’s E.P.A." (Feb. 15, 2018) https://www.nytimes.com/2018/02/15/us/politics/epa-pollution...