this is America. any attempt at this sort of taxation is doa, even as far backs as the 70s. It's like " it worked in Norway (or other small, liberal, or collectivist or highly authoritarian country), it can work America too" um un no.
And clearly taxes that fund roads are soon going to need to be completely revised, since they can't all come from gas anymore.
Whatever the gas tax is replaced/supplemented with, I would be surprised if it doesn't take into account vehicle weight, since the whole point is to fund road maintenance. And remember that road tolls roads already take weight/wheels into account, so there's plenty of precedent.
Heck, NYC is implementing congestion taxes now, if we want to talk about the possibility of new taxes. Nothing "DOA" about it.
There are federal taxes, which generally will be levied uniformly across the country.
There are state, county, and municipal taxes, of which the rates will all vary as well as whether any specific tax is levied at all (eg: Oregon has no sales tax).
Certain taxes will be levied by multiple levels of government, such as gasoline tax which is levied by both federal and state taxes.
Most countries' taxes are far simpler because their structures of governance are simpler, so it's worth keeping in mind that mindset shouldn't be applied to the US.
Any time someone suggests a tax that kind of, sort of, might be, correlated with energy efficiency, it is violating what should be the prime directive of climate change - every gram of CO2 emitted should be treated equally.
Doing studies on the environmental impact of Hummer EVs is missing the forest for the trees.
The minute you establish any category of energy usage that is more pure, more sanctified per unit mass of CO2 output, the invisible hand of the market will shift as much as possible into that loophole, until it is so obscene it can't be ignored. Hummer EVs are just one example.
Focusing on weight is just starting a new cycle of missing the point. My motorcycle is really light, so does that mean it's the most efficient method of transport? Are semi-trailers used because truckers like wasting money?
The counter argument remains: "we must do something...and this is something". I don't need to see that again, but if you have the urge - do you really believe it? Can we achieve any goal through lying about the fundamental criterion of success, by micromanaging out of ignorance?
Everything done to fight climate change is rearranging deck chairs on the Titanic to avoid thinking about the insurmountable political task of raising fuel taxes enough to make a difference.
If you have given up, then there is nothing left but social justice and mitigation for poor countries affected by climate change. So own it. Be clear about it.