Mitsubishi has a terrible reputation for reliability and I'd never own one. Acura has a great record of safety, reliability, MPG, and resale value. The Mustang is another animal altogether and does not really belong with the other two. That being said, I think Ford is building a great car these days but, at $5K, you're looking at an older model likely not up to their current standards. Unless you found a pristine Mustang that's been babied I have to pass. I'd go with the Acura or even a nice Honda Accord or Civic SI.