My sister is a VP over at Matell for the Barbie line. We had a discussion about this a while back, and she told me that their Legal Dept. will go after anybody even using the name Barbie. Doesn't make a difference who they are. Why? Because if the don't, it actually sets a legal precident, and can be used by the defence against Matell in the next case, "You didnt go after XYZ, so why are you going after my client?" These companies are protecting their intelectual property by going after people who copy thier parts or logos without permission. If it has their name or logo on it, it can be taken as the company authorized he manufacturer of that part, and if it fails; well, that just another can of legal worms!
The two companies that I know of that are probably the must agressive in copyright infringement are Caterpiller & Harley-Davidson. In fact, the Pentagon was even getting involved with this for military models. They wanted the model manufacturers to pay a fee to reproduce their equipment. That made military modelers "really happy"!