Actually, the iMac was released in the same year you registered the site (1998). Nonetheless, both emails are spam. They make me want to break into the spam sketch by Monty Python. I hate that sketch, but I hate email spam even more.
I get "let's swap links!" a lot from sites with totally unrelated subject. Occasionally I get an offer to put up advertisements.
I get a lot of russian spam. Lots of it. I get people, or spiders, or bots being referred over from russian websites that when translated are what would appear to be businesses in totally unrelated fields. I figure I'm being targets for being some kind of hacking scheme.
I get the "let me write for your blog" ones too. Just automated spam that is slightly better targeted than the usual crap.
Then there are the "I want to buy ad space on your blog" ones. Yeah, sure you do, on my obscure blog. These usually actually take the effort to look up my contact info, so I think the idea here is an elaborate link farm building scheme. Either that, or the ad will be a virus-infested banner. I never bothered to follow up to see what it's about.
I'd probably hire a lawyer for advice, if nothing else, if I got any trademark claims though. Sure, nobody will confuse your site with car products, and you're probably good, but that's not a given. The style you quoted though doesn't seem very legitimate, and any real law firm would presumably be more formal... so this is almost certainly an attempt to scam you out of a "valuable" domain name.
@Onix: I have gotten spam for kickstarter projects as well. Report it to Kickstarter, it's against their terms. Whether they will take action, I don't know.
DungeonExplorer - I did check with a lawyer ages ago and the law in the EU is quite clear, it's only a trademark problem if there is any cause for confusion. If I create a MacDonald's Woollen Shoppe in Edinburg for delighting tourists with tartan, the golden arches can't do a thing. If I were to sell burgers or use a big gold M, then that's a problem.