Best: 1969 Mach I 428 SCJ. Bought it in 1996 for $10K. It sits in the garage most of the time. Only 57,000 miles. Fast, oh so fast...
Worst: 1977 VW Dasher station wagon. Pretty quick and fun to drive when it decided to run. Sold it and it promptly broke down. Poor guy.
Way back when, I missed out on a 69 Shelby 350. One of the Hertz Rental Cars of the day.
My Dad's “sometime” Business Partner got hold of it and was selling it for $2,000 back in 1974. My Dad told me about the car, so I called the guy and said I would come by the next morning after hitting the Bank to buy it.
Well, the next morning I call him to say I'm going to the Bank and he informs me that some guy came by with the Cash so he sold it out from under me. Almost forty years later and it still pisses me off. I never talked to the guy again.