The 9G-Tronic (internal code W9A, transmission type 725.0) is Mercedes-Benz’s nine-speed automatic, part of the New Automatic Gearbox Generation Three (NAG3) family. It debuted in 2013 on the E 350 BlueTEC before spreading across the lineup: the S-Class (W222), C-Class (W205), E-Class (W213), and the GLE (W166 facelift). Only Mercedes’ V12-engined models kept the older 7G-Tronic.
How it reaches nine speeds with so few parts
The transmission uses just four planetary gear sets, three multi-plate brakes, and three clutches to produce all nine forward ratios – a notably lean parts count for a 9-speed unit. Depending on version, it handles between 400 and 1,000 Nm (295 to 738 lb-ft) of input torque, and supports rear-wheel drive, 4MATIC all-wheel drive, hybrid, and plug-in hybrid configurations across 4, 6, 8, and 12-cylinder engines.
Construction details
The housing is two-piece: a lightweight aluminum torque converter housing paired with a magnesium-alloy transmission case and a weight-optimized plastic oil pan, keeping the 9G-Tronic close to the same weight and installation footprint as the 7-speed it replaced despite the two extra gears. The transmission shaft itself has three parallel oil channels deep-drilled through its core (down to 361.5 mm deep), which both lubricate and cool the planetary gear sets and carry hydraulic pressure to actuate the multi-disc clutches and brakes.
JATCO also builds a licensed version of the same gearset design for Nissan and Infiniti, badged as the JR913E.