2012 Chrysler 300

When it comes to adding transmission gears to boost fuel economy, Chrysler figures the more the merrier. For now.

The U.S. automaker, which is controlled by Italy-based Fiat, will start installing eight-speed transmissions in some of its vehicles by the end of the year, with nine-speed trannies in store for 2013, Bloomberg News reported, citing Mircea Gradu, the automaker's vice president of transmission powertrain and driveline engineering. Eight- and nine-speed transmissions are said to boost fuel efficiency by about 15 percent relative to more conventional transmissions.

There is a physical limit though. ZF North American President Julio Caspari told Automotive News earlier this month that the advancement of fuel efficiency through more gears has just about gone as far as it can go. He claimed that there is just an 11-percent difference between today's best transmissions and a theoretically perfect unit.

Chrysler has sunk $1.3 billion in transmission technology since 2007, which, while substantial, is less than many other automakers have invested in electric-drive technology designed to also meet the goal of boosting fuel efficiency and meeting stricter regulatory standards.