In 1997 Mercedes-Benz founded the premium SUV segment with the launch of the M-Class. At the same time this was the brand's first model to be produced in the USA, at the new plant in Tuscaloosa/Alabama. The first generation of the GL-Class (X 164) with optional third seat row appeared in 2006. It was closely related to the second generation of the M-Class (W 164, 2005-2011) in terms of technology. The second generation of the GL-Class followed in 2012. The name of the full-size SUV was changed to GLS in 2015, while the M-Class was renamed GLE. As a result, this defines the positioning of the two SUV models within the model range analogous to S-Class and E‑Class. Since then, the GLS is the S-Class of SUVs also in the model designation. More than 550,000 units in all have been sold since its market launch in 2006.
First generation (X 164): 2006 – 2012
The GL-Class is presented at the Detroit Auto Show in January 2006 with deliveries beginning in October 2006. Compared with the technically related M-Class, the GL has a wheelbase extended by 16 cm to 3075 mm and with a length of 5088 mm is almost 31 cm longer than the smaller model. The interior enlarged in this way can accommodate an optional additional two-seat bench. The power is provided by turbocharged V6 or V8 diesel engines or by V8 petrol engines.
Like the second M-Class, the first GL has a unibody design, while many competitors are still equipped with a ladder-type frame. It is fitted with leather seats, air suspension with adjustable ground clearance and 7G-TRONIC automatic transmission as standard and in its segment sets standards in terms of comfort and technology. With the model update in 2009, it also is equipped with the PRE‑SAFE® preventive occupant protection system as standard, in addition to getting upgrades to the equipment level and design.
Second generation (X 166): 2012 – 2019
The second generation also is a close relative of the M-Class in terms of technology. While the wheelbase remains unchanged, the vehicle has grown a few centimetres (5120 - 5162 mm). The petrol engines are now twin-turbo V6 and V8 engines. A V6 turbodiesel is alternatively available. The suspension of the smaller engines has steel springs as standard. However, these models can optionally be equipped with the two-chamber air suspension Airmatic with adaptive damping system and automatic level control, which are standard on the more powerful petrol models.
Also available on request are the Active Curve System, stabilisers whose spring stiffness are automatically adjustable for reduced body roll, Night View Assist and Active Parking Assist.
With the model update in 2015, the GL is renamed GLS. The engine output of some models is increased and the 9G-TRONIC replaces the previous 7G-TRONIC automatic transmission in most variants. The assistance systems and the telematics equipment also are brought up-to-date.