19: 1978 Chevrolet C/K Diesel
Today, the GM diesel is one of the most popular pickup truck engines. But back in the ’70s, it was a different story. With all the fuel and emission regulations, the diesel engine in the 1978 model was a travesty (via Diesel Place). The main problem was the reliability of the engine. Consumers generally use large pickup trucks for farm work, but the C/K diesel was constantly in the shop.
The anemic performance only clouded things even further. GM would eventually go to Duramax for their diesel engines, but not before years of unreliable designs had already failed. The C/K redefined styling with a boxy modern style. The ride quality and interior comfort were also at the top of the class. But none of that matters if the truck is not reliable.