Strictly speaking supercars don't need commercials to sell.
So what is the point of having a supercar commercial? Brand awareness is the answer. A supercar commercial allows a brand to create a connection between the badass supercar in the commercial and the rest of the company's product. Case in point the two latest commercials from Chevrolet and Lexus. Both feature the company's quickest, fastest and most expensive product. The Corvette ZR1 and LF-A.
So which commercial do you like better and think does more for its brand?