GM: "Gross Motors", "Gross Materials", Gross Machines".

And because The Admin. wants some balance:
(these are old enough that many of you might not know them.)
Found On Road Dead
Fix Or Repair Daily

And because I love AMCs:
Ain't My Car
Another Mexican Car (I can get away with that one. Look at my user name!)
All Makes Combined

And then the correct ones:
Awesome Muscle Car
Amazing Muscle Car
Amazing Motors Company
(I used to know a lot more of both the positive and negative AMC ones but I've forgotten them.)
Regards, Eric