8. BMW 328d F30
The 328d 3-Series from 2012 to 2018 was a perfect sedan on paper. It was powered by a 2.0-liter diesel engine with 180 hp and 300 lb.-ft of torque. It had an eight-speed automatic and impressive fuel consumption figures. Offered on the American market, it looked like BMW will finally manage to get its customers hooked on oil-burners (via Auto Evolution).
Unfortunately, despite the excellent spec sheet, reliability was terrible. The N47 engine developed numerous problems with timing chains, oil pumps, injectors, and EGR valves which meant that the 3-Series diesel wasn’t there to save you money but to bleed you dry every time you visit the dealership.