The alternator on the left is a Magneti Marelli production unit for a Mercedes-Benz passenger car. The one on the right is the Magneti Marelli racing alternator fitted to the small but powerful Mercedes-Benz IC108E Champ car engine used in the CART FedEx Championship Series. The racing alternator is more than 3.6 kg (8 lb) lighter, almost 76 mm (3 in.) shorter, and nearly 100 mm (4 in.) smaller in diameter than the production unit.