I'd like to nominate the Jeep Cherokee as the most poorly engineered POS ever made. Apparently when it got to 100K, you were supposed to throw it away and buy another. It is hard to work on, parts are expensive and it gets really crappy mileage.
Mine holds the distinction of literally breaking faster than I can fix it. (a week after I replaced the 'trac bar', the heater core split, but while the new boxed core rode in the back seat the alternator burned out).
I told someone that I think I am supposed to just replace parts on it in the driveway without actually starting it, much less
actually driving it. The next day proved me wrong, however. One of the $179 'Wild Country' tires had gone flat overnight. Proving that it could not even manage to sit overnight without something breaking.