http://www.freep.com/story/news/pol...y/news/politics/2016/12/20/license-registration-renewal-fees-michigan/95519264/
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.