what you really need to ask yourself is... do you want good pictures of your car? or do you want to be a photographer?
odds are you can get a camera or rent a camera or borrow a camera and get a halfway decent picture from any of these options, but if you want something a magazine would want to run you're better off hiring a photographer. you'll spend just as much renting pro equipment as you'd spend getting a local photographer to shoot your car, and pro equipment can be next to worthless without a pro to operate it.
if you want to be a photographer, invest in an SLR and take a class at bcc or through pcnw. you don't need a nice slr, you just need one with manual controls. pick up a nikon d100 at glazers and a 50mm 1.8 and you can take pictures that will knock people's socks off with around 50 hours of hobby learning curve time.
then again you can get a single picture worth its weight in gold with less investment than the 'be a photographer' route outlined above.