BMW and Audi to use 8-speed ZF gearbox

[Steven]

The aim for greener cars is up to speed and is showing some promising developments


Audi’s top-of-the line models are likely to feature ZF’s new eight-speed automatic set to roll in next year and the carmaker is already testing vehicles fitted with the fuel-efficient gearbox, according to inside sources. BMW has already confirmed it too will adopt the new design for its 7-series flagship as well as the new X6 SUV crossover.

Audi is yet to confirm the news but analysts at research firm CSM Worldwide have told Automotive News Europe that we’re likely to see the eight-speed ‘box in the A8 saloon, Q7 SUV and upcoming A7 four-door coupe from next year onwards.

ZF claims its new design improves fuel consumption by 14% compared with a standard five-speed automatic because of its longer gear ratio. Engineers have also improved the design to include compatibility with stop-start technology, allowing the close-geared system to shut the engine down when a vehicle comes to a stop and fire it back up and drive off at a moment’s notice.

[WhiteBlue]

amazing! but I guess it will still have higher consumption than a manual

[Steven]

Apparently, the gearbox has also been adapted for use with stop-start technology. This will allow the close-geared system to shut the engine down when the vehicle comes to a stop, yet fire the engine back up and drive off at a moment’s notice when the accelerator is pressed, much like a golf cart.

JustAuto states: "The innovation comes from an addition called a ‘hydraulic impulse oil storage unit’. The unit supplies the necessary oil to the transmission, which stops flowing when the engine is not operating. That oil must be circulating when the gears begin turning, however, for the car to be able to set off again after stopping."
"A reservoir filled with hydraulic oil is fitted with a spring-loaded piston that is retracted while the engine is running and shut off, but once it needs to be restarted, the piston is triggered and it sends the reservoir’s oil into the transmission within 350 milliseconds. This allows for a seamless transition from stopped, engine off to moving, engine on."
"Without the system, the delay to circulate the oil within the transmission would take at least 800 milliseconds (0.8 seconds), causing a noticeable lag in the system."

Ingenious, yet simple

[roost89]

imagine having an 8 speed manual!!
I think those kind of gears are only going to really work in autos and semi-autos.

That's a very good idea though. Fuel would go down a fair bit on british roads since everyone is supposed to stick to 70mph

[Jersey Tom]

8spd sequential box... pure hotness.

[zac510]

As much as I love changing gears I reckon I'd get sick of shifting through 8 during the daily commute

[AeroGT3]

Wow, how pointless and unnecessary. Since since Lexus has one