I'll take Doc - see my avatar. He's got a few miles on him but he's seen a bit of action and can still hold a slide on the loose when he wants to. (I don't think I'm as grumpy as he is early in the film though!)
I love Guido too as does my two year old son who will run around and stop saying "Pit Stop!" in that cute Italianate accent (pretty good for a two year old )
Oh BTW - for those who haven't seen it, Doc is the "Fabulous Hudson Hornet" a great racer from the 50's who crashed when at the top and the sport moved on after he got fixed up - hence the old grump - but he's still a racer at heart and he ends up as Lightning's crew chief.