Fall is going to be a little more interesting this year if you're into cars. By then, Mercedes-Benz will have taken the wraps off its race-bred, carbon-fiber-bodied supercar, the SLR McLaren (left, below). At the same time, those lucky few who plunked down enough simoleons on a deposit for Porsche's race-bred, carbon-fiber-bodied supercar, the Carrera GT (left, above), will start to take delivery of their thoroughbreds. Here's a cheat sheet for the on-the-fence supercar consumer.

Porsche Carrera GT

Engine: 5.7-liter naturally aspirated V10