My biggest worry about cars past the year 2000 are the electrics. My friend here in school drives a Saab station wagon which has been a nightmare in terms of electrical problems.
Her latest one was a dead neutral safety switch. She couldn't start and called me for help.
That and her alarm system freaks out when she locks the car. One of these days I'm going to have to do some searching online for her.
Picking Saab as a story for electrical problems probably isn't the best example, but overall it still worries me.