Eight-Speed Transformation

The first eight-speed automatic transmission in a North American produced automobile will mark its debut on both the Chrysler 300 and Dodge Charger for 2012.

The new eight-speed automatic, previously only found on high-end luxury cars including Audi, Bentley, BMW, Range Rover and Rolls Royce, will be available on selected models of the Chrysler 300 and Dodge Charger. Initially, the transmission will be mated exclusively to the 3.6-liter V-6 Pentastar engine that was introduced last year.

The result is a four mile per gallon increase that pushes highway fuel economy to an EPA-rated 
31 mpg for the 2012 Chrysler 300 and 2012 Dodge Charger—up from 27 mpg highway over last 
year’s models.

The transmission efficiency and wide ratio spread also provide the best possible fuel economy in city traffic. Fuel economy for 2012 Chrysler 300 and 2012 Dodge Charger is 19 mpg on the EPA city cycle—an increase of five percent over last year’s five-speed automatic. With eight-speeds, driving at a lower rpm in both city and highway environments also effectively helps reduce emissions by nearly 11 percent on both vehicles.

A differential with a final drive ratio of 2.65:1 is coupled to the new rear-wheel-drive automatic. The transmission efficiency and gear ratio spread enable spending more time at lower engine rpm, and the use of numerically low axle ratios further improve highway fuel economy.

An optional All-Wheel-Drive (AWD) system features a segment-exclusive active transfer case and front-axle-disconnect system to improve real-world fuel economy by up to five percent. No other major automotive manufacturer offers the combination of these two independent technologies. The innovative AWD system seamlessly transitions between rear-wheel drive and AWD with no driver intervention. When AWD is not required, the system automatically disconnects the front axle to maximize fuel economy while still providing the outstanding fun-to-drive performance and handling inherent in rear-wheel-drive vehicles.


The new transmission required no structural changes to either vehicle, and despite the addition of more gears, the compact and lightweight transmission actually weighs just 6.5 lbs. more than the outgoing five-speed automatic transmission.

The ZF 8HP45 is fully electronic and aided by software that provides an adaptive shifting strategy. It is designed to provide optimal shifting characteristics consistent with the Chrysler and Dodge brands. Adaptive shifting takes into account a number of variables including engine torque gradients, kick down, longitudinal and lateral acceleration, hill detection, friction detection and downshift detection in determining shift patterns. Additional parameters include vehicle speed control, electronic stability control activation and high temperatures that can affect transmission shifting.

The addition of three more gear ratios in the proven transmission design help reduce the gaps normally associated with upshifting and downshifting. Combined with the award-winning 292 horsepower 3.6-liter Pentastar V-6 engine, passengers will experience world-class levels of refinement due to small, evenly spaced ratios that provide quicker acceleration and smoother shifts.

High shifter selection efforts also have been eliminated with gear selection controlled by a shift-by-wire system. The position selected by the driver (P, R, N, D) is transmitted electronically with no mechanical linkage from the shifter to the transmission. Elimination of this linkage removes any shift effort from the driver’s gear selection. Shift-by-wire also allows improved calibration and smoothness of garage and parking lot shifts.All shifts, whether single, double or multiple are performed as a direct result of the pedal position and other inputs. Downshifts are made with very short response times and lead directly to the requested gear. Multiple upshifts can be decoupled temporarily if the torque request changes during the upshift. This helps eliminate the shift “searching” of the transmission.

During more spirited driving conditions, sporty, quick shifts are possible as a result of multiple driver selections and electronically monitored parameters either automatically or through a “sport” shift mode that requires simple driver input. At the rear of the shifter is a gate that allows for down- and up-shifting by the driver. Once the vehicle is in the “Sport“ mode, the driver can use either the console-mounted shifter or a pair of paddle controls located on the steering wheel.

Once the Sport mode is selected, shift times are quicker and shifts occur at higher engine rpm for better acceleration and higher shift dynamics. 0-to-60 acceleration times for the Chrysler 300 and Dodge Charger are 7.2 seconds.

Internally, the ZF 8HP45 transmission features four gear sets and five shift elements (multi-disc clutches and brakes). With fewer open shift elements, drag losses due to multiple parts rotating relative to one another are reduced.

Gear ratios for the transmission are:

Additionally, lower-viscosity transmission fluid is used (P/N 68157995AB*), resulting in improved transmission efficiency and fuel economy especially in cold environments or during vehicle start-up and run. The ZF 8HP45 transmission is also designated “fill for life” and does not require fluid changes during normal driving conditions.

In the event of repair, only Mopar offers a complete line of service parts and repair kits for these and other Chrysler, Jeep®, Dodge, Ram and SRT® vehicles. Mopar O.E. and reman transmissions are fully backed by a 3-year 100,000-mile transferable warranty.

The all-new automatic transmission will be produced by Chrysler at its Kokomo transmission facility made possible by a $300-million investment in the plant.

*Mopar ZF 8- & 9-Speed ATF is formulated as a high-quality fluid specifically for the ZF 8HP45 transmission used in Chrysler Group vehicles. The fluid is approved by Chrysler Engineering to ensure smooth and quiet operation.