The worst thing?
Believe that when you go to sell it that it will be worth at least what you put into it...
Never. Race cars, muscle, classics, always cheaper to buy one done and running.
Not necessarily true. I never buy to flip. Most of the time it seems I hang on to vehicles. However, I have only lost money on one vehicle my entire life. My first truck, which was a 79 Ramcharger S.E. we four wheeled the hell out of that thing, so it more than paid for itself in fun.