To those who remember "three on the tree" or "four on the floor", today's seven and eight-speed automatic transmissions seem to offer a bewildering amount of gears to choose from.

Chrysler will go one better in 2013 with a nine-speed automatic transmission, as the maker looks towards improving transmission technology as a way of creeping towards the 54.5mpg 2025 Corporate Average Fuel Economy targets.

Several carmakers now offer seven-speed trasmissions--sports car maker Porsche even offers a seven-speed manual--while a select few also supply you with eight gears.

If you've not driven a car with that many gears it can sound excessive, but it's actually very effective at meeting the twin targets of performance and efficiency that many buyers seek.

Where an old five or six-speed automatic might occasionally find itself "between gears"--i.e. a situation where one gear doesn't offer enough power, but the one below is revving too high, wasting fuel and offering limited acceleration before another change up--seven and eight-speeders are more likely to be in the right gear, more of the time.

That means they can quickly and smoothly change up to very high gears at a cruise (improving economy), but there's still a broad repetoire of gears to choose from should you flex your ankle for a bit more power.

Chrysler already offers an eight-speed auto, in the Dodge Charger and Chrysler 300. Highway economy improved by 15 percent in each when those models gained the new transmission, with very respectable 31 mpg highway from the 3.6-liter V6.

Gearbox builder ZF, who'll make the new 9-speed, predicts a 16 percent improvement in vehicles like the Dodge Grand Caravan. According to Automotive News, all Chrysler's front-wheel drive models will be considered for the 9-speed transmission, while rear-drive vehicles will get the 8-speed, licensed from ZF.

Surprisingly, the 9-speed unit shouldn't be appreciably bigger than existing transmissions, as Chrysler is considering it for the Dodge Dart compact, as well as Dodge and Chrysler minivans, and some future Alfa Romeo models.


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