My '06 tC is still mechanically great after 75k miles but the body has seen better days, especially after being parked on nyc streets every day. I got the typical front/rear scratches and a few door dings here and there, with a few spots that might need paint touch-ups. I'd like to make the body look as new as possible. What's the best way to do this? Would the cost involved in this not be worth it?

 

Pull the front/rear bumper and side molding yourself, prep them with sandpaper to smooth out any imperfections and then take them to a body shop to have painted. Once done, reinstall the bumpers and side pieces yourself. Most of the fees associated with painting is labor. If you do all the prep work yourself and remove the pieces then you'll safe have the cost. Paint and painting is the cheap part....HTH

 

get a bar of clay. clean clean clean clean, then buff/wax the surface. automotive clay will do wonders to the finish. takes a good amount of time to do it right but it will help especially if u have never done it before

 

Clean, Correct, Protect.
Wash (removes heavy/loose/"large" dirt). Clay (removes bonded contaminants and "fine" dirt). "Cut/polish" can be done by hand or machine, machine is much faster but can be intimidating for first timers. "Cut" implies a heavy cutting compound like Meguiar's 105 this can take a little time since heavier compounds tend to dry faster but if you are working by hand I wouldn't worry too much, "polish" usually implies using a fine or "finishing" polish like Meguiar's 205 to remove and marring created by the "cut" step and to bring up the gloss and depth in the paint. Ideally you shouldn't need "cut" the paint every time. After the first "heavy duty" paint correction, the user can prep the finish with a paint work cleanser or cleaner wax before protecting with a wax or sealant. Protect the paint with a good carnauba wax. Be aware of cleaner waxes that use the word carnauba in their name, they don't protect very well and are mainly meant to clean the surface. Look for a "pure wax" like P21S Concours-look or PoorBoy's Natty's Paste Wax (both are good bang for your buck wax, that looks great). Or some people prefer the look and "performance" of a synthetic paintwork sealant. Sealants are typically more durable than carnauba wax's but they don't offer as much warmth in the looks department. Too many sealants out there to list but I have enjoyed using Menzerna PowerLock, Chemical Guy's JetSeal109, and Opti-seal to name a few.
After putting all this effort into making the car look great, for the love of god, take care of it. Wax at least every 3-4 months. If you can wash it monthly, great! but, wash habits are usually dictated by driving habits. Minimize the damage to the paint by taking time to do the proper wash steps. Remove bird droppings or other foreign materials as soon as possible.
Hope this helped. If you have any more questions please feel free to shoot me a PM.
Good luck and happy detailing
-Rob