I recently decided to paint the engine hood and roof of my car because color faded and turned from black to grey and actually I had a two color car. I didn't expect the color to fade so soon since I own the car only 4 years but this propably happened because I used a cover in the winter.
I wasn't sure if I should paint only the faded parts beucase there is always a risk for the newer painted parts to differ from the rest of the car.
I also painted a part of the rear bumber.
At the end I was very pleased with the result. Here are some photos: