IMO, GM holds the record for engineering that just didn't quite work out as planned. As examples:
The flat six Corvair. Never drive behind one if you don't want the front of your car covered in
oil.
Pontiac Tempest with the flexible drive shaft. Now that was an idea that whent nowhere.
Pontiac Fiero, 2d gen. Car ran so hot, it had to have a seperate cooling fan pointed at the distributor just to keep it from a melt down.
Caddy 4-6-8. Well, what else is there to say about this one.
V8 Monza. Had to unbolt the engine mount in order to change the spark plugs.