As far as I understand it the copyright applies more or less only for electronically, and preferably (but not exclusively) musical, designed sound. Like the ringtones from polyphonic/PCM-cellphones to name one thing. When it comes to Zippo's, Cadillac doors, Harley-motors, the buttons on a Nintendo NES, et cetera, it is, still as far as I know, like taking a photograph or filming. You don't need an permission from Mercedes to use their cars in movies. :-)
They might however get well pissed if the name shows in unfavorable scenes. Shouldn't be a problem with sound though.
You rarely see brand-names when buying sound effects, but frankly I think it's more because they don't wanna tip off competitors! When it comes to vehicles, I think pretty much all my bought sound effects are named by brand and model, and actually in many cases even year of make or revision. In my Steinberg Nuendo Sound-collection every single sound is named by exactly where it came from :-)