Electric vehicles, or cars that are not capable of using gasoline and other traditional fuels, will be subject to an annual $100 surcharge, in addition to a $35 gasoline tax. Owners of the Chevrolet Spark EV, Bolt or Ford Focus Electric, for example, would experience that estimated $135 registration fee hike on top of their usual registration fee.
Owner of hybrid vehicles will pay a $30 surcharge on top of registration fees, plus a $17 gasoline tax. Hybrids are considered any vehicle “that can be propelled at least in part by electrical energy” while using a battery storage system of “at least four kilowatt-hours,” according to the law’s language.
Based on my gas/electric percentages and how much I drive per year, I estimate I'll pay $7 more in gas taxes plus the $30 & $17 fees for a total of $54 more next year.
Compare that to my minivan where I drive about half as many miles and get half the mpg as the Volt. I'll pay about $58 more in gas taxes next year.
So basically, the rule is a) drive your most efficient vehicle at all times, and b) keep the Volt charged as much as possible.