So far mine is a 2005 Grand Prix. I've owned it for a year now and bought it with 54,000 miles. It now has 73,000 miles and have replaced the following: Tie rods/sway bars were worn causing clunking, shaking, and uneven tread wear. Engine was over heating at stops: New thermostat, coolant flush and ended up having to replace water pump. New problems: A valve cover is now leaking oil, slowly. My passenger front wheel bearing is getting worn out. My transmission is now clunking going from reverse to drive. The best part is the engine, good power and good fuel economy and is comfortable for my 30 min commute to work. With that being said though, it will be gone within a year. Whats your most problematic car you've owned?