Any one use a Porter Cable machine on their cars to polish, etc.?

There are a lot of polishers out on the market. The keys to getting good results are a random orbital polisher, good bonnets, a light touch, and plenty of practice. If you've never used an orbital polisher before, I would recommend that you practice on an older car to "polish" your skills .:p

With that said - Porter Cable makes excellent power tools. I've had plenty of good luck with their products, everything from sanders to drills.

Like red_base said, any good orbital polisher will do but the key is practice, practice, practice. You can do serious damage to a car's paint if you are not careful. I detailed cars back in high school and made numerous mistakes while learning the art of buffing.

This being said, you need to remember that frequent hand polishing/waxing of your car will for the most part suffice in keeping the finish in great shape. The buffing compound typically used in polishing are abrasive and essentially wet-sand the car to remove oxidation and other paint contaminents. Frequent buffing will only damage your paint.