It started with some Le Mans test cars with an unpainted carbon fiber body.  Cars with racing pedigrees are using a single primer coat to lessen the weight for getting absolute speed ratings during circuit testing.

The Maserati MC12 test car as well as its sibling the Ferrari 575 GTC Evoluzione seems to have started the matte finish craze when they landed on the sports front pages.  Now you see them on the road.

Matte blacks, matte whites, matte just about every color.  Do they look good?  Some do.  Others can look awful where it seems the owner forgot to finish the body leaving just the grey primer coat.