Price: $8 Million

Like many others before it, the Mercedes-Benz Maybach Exelero is a one-off. Commissioned by Fulda, a German subsidiary of Goodyear, to test its new tires, the Exlero debuted in 2004. Mercedes built the Exelero on the bones of a Maybach, and gave it the same twin-turbo V12 engine producing 690 horsepower (510 kilowatts) and 752 pound-feet (1,020 Newton-meters) of torque. Top speed is listed at 218 miles per hour (350 kilometers per hour) and adjusted for inflation, the Exelero would cost more than $10 million in today's money.