To meet the congressionally-mandated CAFE (Corporate Average Fuel Economy) requirements through to 2020, no aspect of automotive design remains untouched. New engine technologies have been front page news for some time now, but the car’s transmission is a strong candidate to improve mileage.

Recent materials published by Chrysler for the Dodge Charger V6 showed an improvement from 18/27 city/highway to 20/29 when the ZF eight-speed automatic transmission is installed. Although the numbers are yet to be confirmed by EPA testing, performance improvements for the V6 Charger should be evident as well.

Photo: ZF

With correctly selected gear ratios, transmissions like this can keep the engine running within its optimal power range. In manual transmission form, such ‘close ratio’ gearboxes have been used for decades in competition. ZF and Chrysler are going at least one step further with the announcement of a 9-speed automatic transmission.

Using a modular design approach, the 9HP gearbox can be configured for regular, hybrid, stop-start and all wheel drive usage. Both smoothness and performance are important and ZF began by designing all control components for shorter response and shift times, apparently below the threshold of perception.

Shifting points and shifting dynamics are highly programmable – from high comfort with best fuel consumption to extremely sporty – the shifting sequence control exposes all clutch controls, adaptation functions and transmission protection functions for programming.

Compared to current 6-speed automatic transmissions in front drive/transverse engine installations, the 9HP can generate up to 16 per cent higher fuel economy, according to ZF. The transmission uses a conventional torque converter for startup, quickly jumping to a locked-up state to minimize losses.

Chrysler expects to build about 650,000 of the 9HP transmissions annually under license from ZF. An additional 150,000 8-speed transmissions will be built as well.

Photo: ZF