So, your car needs a little bit of bling? Well here is how to do it the non expensive way ;)

1. Select around the part you want to chrome (I decided to be different by doing a chrome hood ;) )
http://img393.imageshack.us/img393/1858/chrome1ab5.jpg
Copy and paste it into a new layer.

2. Desaturate that layer, and duplicate it (Ctrl + J)
http://img393.imageshack.us/img393/6355/chrome2lt2.jpg

3. Select the hood (Hold control and click on the hood layer in the layers box)
and fill that with white.
http://img393.imageshack.us/img393/3876/chrome3vu4.jpg
Change the top layer (White) blending mode to overlay.

4. Amazing results. (Not too good on this one, but works well on parts with lots of reflections).

http://img104.imageshack.us/img104/3417/chrome4nv9.jpg

-Chris-

Hope that Helped ;)

http://img181.imageshack.us/img181/1497/chromecfkm5.jpg

thats more like it (i was messing around with a chrome carbon effect.)