What does “a mission to make the 1 percent 100 percent able to indulge in car elevators” mean?

Solution 1:

NOTE !!!: I'm in NZ. I do not participate in US politics. I just stand bemused at a great distance and scratch my head. Down here at the bottom of the world I more and more tend to not vote for anyone major.

"The 1%" = the richest 1% of the population = "the very richest people".

"The 99%" is also a "code" or slogan from the "Occupy Wall Street" campaign that suggests that the top 1% of the people are getting the most benefit from the system while the workers (ie 'us') constitute 99% of the population.

"100% of the 1%" = all of the very richest people. ie none of the very richest people are excluded.

"Car elevator" = literary a means of lifting your car to a higher level in your house but here means "an exceptionally expensive and showy luxury item".

Taken overall = "Wants to make every one of the very richest people much richer so that they can all afford very expensive showy luxury items". The implication being that this is achieved at the expense of the 99% non-richest people.

Overall short translation - "Romney is out to make the rich much richer at your expense".

Solution 2:

It means that she thinks Romney is planning to make make wealthy people such as himself wealthier.

The '1%' is the wealthiest 1% of society and having their own car elevator is a status symbol beyond the reach of most, but Romney has one. Romney (allegedly) wants to ensure that 100% of the 1% are also in a position to afford one.

Solution 3:

Looking at your quote, it doesn't seem to be meaning "100% of the 1%". Rather, I think it means "he’s on a mission to make the very rich (1 percent) fully able (100 percent able) to indulge in car elevators.”

100% is often used to mean "totally", or "fully". However, 110% is more common, even though some think it's a bit hyperbolic.