My ex-wife worked for the VP of PACCAR (Peterbuilt and Kenworth. He was the lead corporate attorney and along with the other 6 staff attorneys they all focused their efforts on copyright/trademark/patent law.
When they had similar cases it was usually because they were using a copyrighted logo or trademarked symbol.
On a side note, you should have seen all of the swag they got from companies looking to market products using PACCAR products. From ball point pens to folding knives made by the Franklin Mint. Another cool thing was they got to review the movie scripts where their product would appear. If it showed the product in a favorable light then it would be approved. If it showed them in a bad light the symbols, logos, and names would have to be removed.
I actually got to read the original script from Smokey and the Bandit.
Gosh, you'd think they would have at least asked them to paint the Peterbuilt in the truck horror film "Duel."
Cripes, what a nasty looking rustbucket.