I think the only vehicle that I have ever seen that I consider correctly or under powered is the wildfire and I can't bring myself to get one.
*edit* that was meant for ryandpotter. now my post makes more sense.
My Buick is underpowered. It used to be a lot worse, but when I switched out the transmission I put in one with a lower first gear, and a taller high gear to make it more driveable. It used to be that a Yugo could blow me out of a traffic light, but once you get that car rolling its great on the highway.