i think its total bullshit..
if that were the case, there would be thousands of websites having to change their url because they have a companys name or logo incorporated in theirs.
www.nissan.com isnt the car company and they have been up and running long b4 i was really into cars, i think the only way they can make anyone change anything is to buy out the domain. you bought it, its registered to you, tell them to take a hike