Hi,
I signed up just to post this - I've been lurking for quite a while though, so it's about time I start posting. Anyway, I'm an amature web designer, so I figured I'd pitch my comments if you don't mind.
First, the edges of your title and buttons (on the right) really look unprofesional. Just feathering out the edges of the buttons, like this, makes it look a lot better (IMHO):
http://www.mortifiedpenguin.com/camaro/grayoval1.gif
The same goes with the title at the top. I know it's just text, but the edges of the font really looks choppy and, well, like a geocities site (no offence).
I would take that lettering into an image program (Paint Shop Pro, Photoshop, etc.) and just recreate it there, and save it as a .gif file - that alone should clean it up. Something like this would look cleaner, if you ask me:
http://www.mortifiedpenguin.com/camaro/grayoval1.gif
Lastly, and you know it's coming... Geocities. It's home of the 12 year old's personal website. Not only does a geocities.com/* URL look very un-pro, but the ads on the right draw attention from your site. They seem to be contextual, meaning they match themselves to the context of the website, so they could possibly show auto detailing websites - sending visitors to your competitors sites (some ad campains do even allow you to target local visitors).
Hosting isn't expensive, so long as you don't use a rip off like Yahoo or something. I use a hosting company that charges $4.95 per month, and is very reliable. Plus, you get a free domain name, so you can be DK-auto-spa.com or something - which makes you look MUCH more profesional. If a guy was going to do my car, and wouldn't spend 5 bucks a month on a website for his business - I'd be very afraid about what corners he might cut when it comes to my car.
Here's a review of the hosting company I use, it pretty much sums up all of the details:
http://www.web-host-reviewing.com/ixwebhosting.html
Other than that, great site man. I love the "My Car's" and "Customer's Cars" - looks really great. Looks like you do some really nice work too!
edit: I know, I know, I'm a perfectionist, but hey - this is Autopia after all.

Anyway, just noticed the pictures of the cars on the sub pages - yellow M3, silver porsche, etc. that have a white border around them. Some time spent in a graphic editing program with a black pinsel could make those borders look a lot nicer
