Mercedes-Benz has been accomplishing miraculous feats of incredible horsepower with its large displacement engines. However, those engines haven't been particularly fuel efficient, so M-B is in the process of developing several new mills to meet new CO2 and fuel economy standards in Europe and the U.S.

Mercedes is reportedly adding a new, direct-injected, twin-turbo 4.7-liter V8 engine this fall with an impressive 435 horsepower and 516 pound-feet of torque. The German automaker claims a fuel economy improvement of 22 percent versus one of its last-generation engines outputting a similar amount of power. Those impressive gains come courtesy of the aforementioned direct injection, stop/start technology and more efficient components like the fuel and water pumps. The twin-boosted V8 will reportedly arrive this fall in the CL-Class and S-Class.

Also up for an overhaul is Mercedes' 3.5-liter V6. The new mill will have an all-new 60 degree V block with new intake and exhaust. The sum of these changes is 306 horsepower and 273 lb-ft of twist, and a reported fuel economy savings of 24 percent in the not-for-U.S.-consumption S350. The new 3.5-liter will be an especially welcome addition to the Mercedes lineup, as the current 268 horsepower engine isn't exactly keeping up with similar displacement engines available from Lexus, Infiniti, Cadillac and Acura.

Keep in mind that Mercedes isn't listing official EPA numbers when its touting its new engines' improved efficiency, and Inside Line points out that the EPA rating system doesn't really account for Stop/Start systems in its fuel economy averaging.

[Source: Inside Line]