Porsche wasn't allowed by Peugeot in the 1960's to call it a 901 because they had the right to a zero as a second digit in the French market, and that's why we know it as the 911. Corporations pay big money for brand loyalty and hold huge goodwill values for these names. The F150 is only big in America, but it's significantly big. So they WOULD sue.
Waisay I don't know if anyone remembers, but the Ferrari Enzo was called the F60 originally, and Ferrari's F1 car for a later season was also called the F60.