Chrysler's upcoming eight-speed sedans will come with a 31mpg highway rating.

It wasn't all that long ago that the 30mpg club was reserved for compact cars, but two full-size muscle cars will be receiving their initiation later this year.

Chrysler hasn't been shy about promoting the fact that its two full-size sedans - the Chrysler 300 and Dodge Charger - will be receiving a new eight-speed automatic transmission this fall, but has been reluctant to reveal any concrete fuel economy numbers. However, Chrysler CEO Sergio Marchionne recently let slip just how efficient the new gearbox will be.

According to Marchionne, V6 versions of the 300 and Chrager equipped with the new eight-speed unit will be capable of 31mpg on the highway. That represents a 4mpg improvement over the current car, and even bests vehicles like the Honda Accord V6.

It remains to be seen if the all-wheel drive versions of the 300 and Charger will receive the same 31mpg rating, but our sources at Chrysler have indicated a front-wheel decoupling system will allow the same highway ratings across the board.

The ZF-sourced transmission will join the 300/Charger lineup by year's end, with the eight-speed unit expected to be offered on V8 models in 2012. Assuming that 15 percent fuel economy bump carries over, the V8-powered cars could offer up to 29mpg highway to go along with their 370 horsepower.


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