Washington, D.C., USA – Toyota and BMW cut their cars’ carbon dioxide (CO2) emissions rates while taking larger slices of the U.S. automobile market, according to a recent report.

Environmental Defense’s report, Automaker’s Corporate Carbon Burdens: Update for 1990-2005, found the two automakers defied a larger trend of auto manufacturers growing vehicle-related emissions rates during the 15-year period — a trend led by General Motors Corp., Ford and DaimlerChrysler.

“The ability of Toyota and BMW to gain market share while cutting emissions is a clear example of innovative design paying off for the bottom line and the environment,” John DeCicco, senior fellow for automotive strategies at Environmental Defense, said in a statement.

BMW led the pack by trimming CO2 emissions from its fleet by more than 12 percent while its U.S. sales enjoyed a fourfold increase. The company achieved this in part by improving fuel economy of its 3-, 5-, and 7-series models, and M sports coupe and sedan models. The biggest driver, however, was the success of the Mini Cooper, which emits a quarter less CO2 and accounted for one-fifth of the company’s 2005 new fleet sales.

Between 1990 and 2005, Toyota’s market share grew by 7 points while its fleet’s CO2 emissions rate dropped 3 percent because of greater fuel economy for passenger cars.

Its “carbon burden,” a measure of the average annual CO2 emissions during the lifetime of a group of vehicles, grew by 125 percent, which was more than the other five largest manufacturers. This, however, was due to an increase in sales.

The average CO2 emissions rate of GM’s fleet grew 3 percent while its market share dropped 10 points. Its carbon burden remained the largest overall of the top six automakers despite a 6.5 percent decrease.

Ford’s carbon burden dropped almost 6 percent because it lost seven points on market share. Its emissions rate increased nearly 5 percent.

DaimlerChrysler, with the largest truck fleet overall, saw a 4.8 percent boost in its fleet’s emissions rate. Honda, with the best average fuel economy of the six largest automakers, saw its emissions rate grow by 4.4 percent because of increased truck sales.

Overall, vehicle-related emissions have grown steadily since 1990 despite a slight 3 percent dip in CO2 emissions between 2004 and 2005 — the first decline in 20 years. A average emissions remained up a net 1.5 percent since 1990.

“A complete climate policy solution for the auto sector is one that results in progressively lower carbon burdens,” DeCicco said. “This can only be accomplished through climate-friendly innovations in both vehicles and fuels.”