How difficult would it be to add heated front seats to a 2003 CLK500?
Has anyone done this?

 

if you want everything factory, then you will need new leather heated covers, wire harnress and switch row. If you want to cut corners, then original harness, switch row, and heated elements under the current leather covers.

 

I actually added heated and cooled seats to my old 2003 C230. It was a challenge but not too difficult. If you're just adding heat its even easier then cutting out holes and adding fans for the cooling. Hardest part is getting the leather seats to fit like factory again afterwards because the clips are so darn hard to put back in place. I posted an install with picts awhile back. Let me know if you need help.