My 4 year old is the same way. He has a '02 Porsche Carrera that looks like it was car jacked, stripped and left on the street....... a '67 Fastback Mustang that has all the glass cracked out, all the mirrors and air ducts glued back on dozens of times and a '70 Barracuda that has me considering buying stock in a glue company. I've practically spent more time fixing and gluing those car back together than I have spent on my own car !!! He owns over 200 Hot Wheels and various other small cars that are in every room of my house (you should see his bathtub collection!!) We buy him the cheap ones at the car shows etc since we know "look but dont play with", will never fly.
Watching him race them around the house making car noises....priceless....
He's like my little best friend when it comes to cars. We drive around and he starts screaming "dad, dad, dad, look, look" when he sees an old muscle car drive by or a new corvette of mustang. He pages through my car magazines and can name a good portion of the "well known" cars (mustangs, camaro, challenger, barracuda, chevelle etc etc).... it makes my wife sick

... he knows more cars than she does.
He also know who Chip Foose is and gets excited when his show or his commercials come on. He says he wants to grow up to draw cars like Chip.
My wife is scared that our daughter will be that way too since she spends 2 days a week at home with dad....
He's still too young to really help or be safe in the garage around some of the stuff I'm doing, but I can hardly wait until then. Hopefully he's still into it later on.