ZF 8HP eight-speed automatic

What it is

The 8HP is a longitudinal eight-speed automatic transmission for rear- and all-wheel-drive cars. It was one of the first eight-speed automatics in volume production and has been developed through several generations, now including plug-in hybrid versions with an integrated electric motor.

How it works

Like other automatics it uses planetary gearsets, but ZF arranged four gearsets and five shift elements so that only two elements are open in any gear. That reduces drag losses and allows eight ratios in a package similar to earlier six-speed units. More ratios let the engine run closer to its most efficient speed. In hybrid versions an electric motor sits in the transmission housing, so carmakers can electrify a model without redesigning the drivetrain.

Why it stands out

• Production began at Saarbrücken in July 2009, and ZF claimed an 11 per cent fuel economy improvement over standard six-speed automatics.
• In 2019 ZF announced an order from BMW for the next generation with a value in the double-digit billions of euros.
• Saarbrücken is the lead plant; ZF also builds it in Gray Court, South Carolina.

The fourth generation, designed in Friedrichshafen, started production in Saarbrücken in 2022, and ZF said in 2024 it would invest a further 500 million dollars at Gray Court to build the plug-in hybrid version for North America. That modular approach, one family adapted for combustion, mild hybrid and plug-in hybrid cars, is the reason the design has lasted so long in a market that usually replaces gearboxes far sooner.

Where you meet it

CarExpert lists the 8HP across BMW's rear-wheel-drive range, in certain Audi models, in the Jaguar XE and XF and in the Alfa Romeo Giulia and Stelvio. Many drivers of quite different brands are therefore shifting through the same German gearbox, a fact rarely mentioned in a showroom.

Sources

• CarExpert: Inside the suppliers, ZF
• ZF via PR Newswire (2019)
• Just Auto: ZF's Saarbrücken plant
• Wikipedia: ZF Friedrichshafen