What happens when you subsidize technology and then have a deficit in government?  You tax the people you just paid.

In Washington state, after years and millions of dollars in tax breaks to purchase electric (and hybrid) vehicles to make it at least close to economically feasible for mainstream drivers, the government has realized something horrible - those drivers aren't using enough gasoline, which means they aren't paying enough in gasoline taxes and, with a $5 billion deficit, that is bad.

Plus, if you're an electric vehicle owner, you can't really object when a politician - especially one you voted for - says you still aren't doing your fair share for the environment.   

"Electric vehicles put just as much wear and tear on our roads as gas vehicles," said Democratic state Sen. Mary Margaret Haugen, the bill's lead sponsor. "This simply ensures that they contribute their fair share to the upkeep of our roads."

That sentence will create a few Republicans.  Hybrid and electric car owners thought they already were doing their part by saving the environment, but road repair creates emissions too and a nice $100 fee can offset that.    Once electric cars came into existence, it only made sense an advocacy group would be created to lobby for the new special interest.    Enter Plug In America which is, no surprise, against a fee for its members but, if one will be imposed, they want it to be mileage-based; because electric cars can't go more than a hundred miles anyway, which is why few people want them.

Tesla Roadster
Exception:  If the government is willing to subsidize it, I am perfectly willing to drive this $109,000 Tesla Roadster.  0 to 60 mph in 3.9 seconds with a 200 mile range.

 There is no objective metric that says trading global warming for acid rain is superior for the environment, any more than trading OPEC for a utility company is better for the environment, but if governments sense that rich people driving electric cars can pay more, they will pay more.   And they can pay more because they have no choice, since they already bought the cars.