RennTech ECU Upgrade HHT Tuner 2017-2019 Mercedes-Benz GLS 450 X166

The 2017-2019 GLS 450 leaves a lot on the table with its 3.0L M276 twin-turbo V6. RennTech, the Florida tuning house founded by former AMG engineer Hartmut Feyhl, measured this engine at 362 hp and 384 lb-ft stock, and its ECU file lifts it to 402 hp and 454 lb-ft at the crank. That is +40 hp and +70 lb-ft, with most of the torque gain landing in the midrange where a three-row SUV spends its life: merging, passing and towing.

See how the RennTech HHT works

Features

• Loaded through the RennTech HHT hand-held tuner, which plugs into the OBD2 port, so the ECU never comes out of the car
• The HHT stores both the RennTech file and your original factory file, so you can flash back to stock and back again as often as you like
• Flashing takes a few minutes in the driveway
• Calibration covers ignition timing, throttle mapping, fueling and boost across the whole rev range, tuned to keep daily-driving manners intact
• RennTech states its M276 BiTurbo ECU upgrades are TÜV approved

What is included

• RennTech HHT hand-held tuner loaded with the GLS 450 calibration
• OBD2 connection to the vehicle

Specs

Fitment notes

For the X166 GLS 450 4MATIC with the M276 twin-turbo V6 only. It does not fit the GLS 450 on the newer X167 chassis or the GLS 550 / GLS 63. RennTech notes that the M276 often measures above its factory rating stock, so gains are calculated from its own measured baseline. Your VIN is required with the order.

Fitment