If the GV overdrive had the same overdrive ratio, I would possibly consider it.
But at 15000 miles a year with 20 miles to the gallon and gas at 6 dollars a gallon, the break even point for the GV at $3k would be over three years.
Since most of us are not going to get 20 mpg and we will drive less than 15000 and hopefully gas does not make six dollars, payback will be even further into the future. The A500 at half the price and better ratio makes better sense to me.