HEMI engine ring
I'm rather fond of this "HEMI Blown with Ruby's" ring from Cruzin' World (dot com), but I'd prefer that they ditch the rubies in the blower for some cheap crystals so that it didn't cost $400. Still — badass.
HEMI ring catalog page [CruzinWorld.com] (Thanks, Confused or Surprised!)

the latest
latest episodes

More car related... and motorcycle themed as well.
Tire Rings -
http://www.tirerings.com/showcaseindex.html
http://gandolfi.deviantart.com/art/V8-Engine-18732983
If I had the money, I'd rather get this ring.
If Liberace had been a race car enthusiast...
Badmotorfinger?
Here's a more symbolic representation of V-8 love.
http://onetoomanydesign.com/jewelry/rings/V8.html