Why Do So Many Cars Have 8-Speed Automatic Transmissions Now?

Eight-speed automatic transmissions are common — they're used in many vehicles currently on sale. Many manufacturers use these eight-speed automatics because they hit the "sweet spot" where performance and fuel economy both improve. That's a winning combination. 

The first eight-speed automatic was Aisin's AA80E in the Lexus LS460 in 2007. The most widely used eight-speed is likely the ZF 8HP family of transmissions, one of the best transmissions ever offered on a production car, which has been around since 2010, when it debuted in the fifth generation of the BMW 7 Series that was equipped with the V12 engine. Its initial use in BMW's flagships, the 760i and 760Li, demonstrated added flexibility and higher efficiency. The 8HP was also lighter than the previous six-speed automatic and fit in the same space. Other automakers soon adopted the 8HP, with even manufacturers of sports cars like Aston Martin adopting it for its quicker shifting speed. Many mechanics say the ZF 8-speed is one of the most reliable transmissions, and we will focus on it due to its wide use in so many vehicles.

There are other eight-speed automatic transmissions. Hyundai followed in 2011 with the A8LR1 and A8TR1. General Motors' Hydra-Matic 8L90 was first used in the 2015 C7 Corvette Stingray and Z06. Toyota also introduced one in 2016: the FF 8-speed Direct Shift-8AT. Today, various models of the Tacoma, Highlander, Grand Highlander, 4Runner, and Land Cruiser have an eight-speed automatic.

In addition to Aston Martin's Vantage shown above, the list of vehicles that use or have used ZF's 8HP line of eight-speed transmissions is long. It includes many BMWs that have ditched DCTs for the traditional ZF, the current Toyota Supra, some Jaguars and Land Rovers, the Rolls-Royce Phantom, the Alfa Romeo Giulia Quadrifoglio, and the late, lamented Chrysler 300, which was its first use in an American-branded car back in 2012, along with the previous Dodge Charger. Chrysler, now part of Stellantis, has been making the ZF eight-speed under license since then, with millions produced and under the hoods of a wide variety of the company's products, even those powered by a Hemi engine. 

The ZF 8HP transmission can handle some pretty high levels of torque. Depending on the transmission type, the ZF 8HP can manage torque from a low of 221 lb.-ft. to a maximum of 737 lb.-ft., which helps explain how it landed in both an Aston Martin and the 600-horsepower 2027 Dodge Super Bee.

Overall, the ZF 8HP eight-speed transmission has become known for both the speed and the smoothness of its shifts. This has led to the ZF 8HP taking the place of even some dual-clutch transmissions, which cannot approach the effortless transitions between gears that are delivered by the ZF unit. Combined with the large number of different gears in the ZF transmission, this delivers a level of performance that manual transmissions are no longer capable of.

The ZF 8HP gives drivers a very high standard of shifting feel. The transmission uses three clutches, four gearsets, and two brakes to generate eight speeds. It can also skip multiple gears if its logic circuits say so. This transmission is designed for longitudinal use, meaning it is for engines set up to drive either the rear wheels or all four in an AWD setup. The racing version of the RWD BMW 2 Series — which we found too good to be true – shows the 8HP's shift lever and its paddle shifters, which allow more precise control of the automatic transmission than you can get by using its lever alone.

While the ZF 8HP can be a great transmission to drive, it can have some problem areas. These start with its exceptionally complex valve body, which can be subject to a leaking pressure regulator valve, a leaking priming valve, or moving valve body end plugs. Deteriorating solenoids are another issue. Then there is the Mechatronic system and the TCM, both of which live inside the gearbox in very hot conditions. Most of these problems can be prevented with improved fluid maintenance procedures. Other issues involve the torque converter, the bushings, and the various clutch assemblies, which can be tricky to address.

The ZF 8HP transmission is used in a wide variety of vehicles made and sold worldwide. It offers drivers an excellent combination of fuel economy, smooth shifting, and performance when you need it.