Driving around in the area I just moved to, I have noticed a LOT of gorgeous vehicles. Some, even though they've been around for a few years, I still find their designs timeless.
One of the modern cars I would suggest would be Vipers, specifically 1st and 2nd gens, GTS screams sex appeal and aggresiveness, curves galore. Definite classic and especially being a raw drivers car in a time of techy devices and controls.
I love how Corvette Stingrays look (all of them). I don't think that the C4s-C5s are timeless at all, they're just wedge shapped. The new C6s are hawt but I dunno...
I agree 100% with the 911... awsome design.
Cars from the 50s and 60s with fins and lots of chrome.. I like. However I really don't care for late 60s-70s muscle/pony cars all that much for some reason. Love the last 60s Mustangs though, they aren't as boxy.
The BMW Z8 still takes my breath away in a way usually reserved only for things from Maranello. This car was so gorgeous they needed to bring in the likes of Chris Bangle to restore entropy to the universe.