Automobile companies seem eager to claim that they have the most fuel-efficient vehicles, but they can't all be tops. Data from the U.S. government show that car fleets from Japanese firms Toyota and Honda have consistently been above the Corporate Average Fuel Economy (CAFE) standards that manufacturers are supposed to meet (small graphs below). Historically, the big U.S. makers—GM, Ford and Chrysler—have hewn close to the standard. Firms such as Porsche that focus on high performance tend to fall short. “They pay the fines,” says Brandon Schoettle, sustainability project manager at the University of Michigan Transportation Research Institute. “And they probably work that into the price of the car.”

See details on fines, and how companies use credits to help meet CAFE standards, at