Mercedes-Benz Introduces 1.5-Liter M 252 LS Engine With Electric Turbocharger for the GLB 250

Mercedes-Benz is expanding its electric turbocharging technology beyond high-performance AMG models to standard passenger cars. Originally introduced in the Formula 1-inspired AMG One hypercar before reaching the AMG 43 and 63 lineups, an electrically assisted turbocharger is now making its debut in regular models through the new M 252 LS four-cylinder engine, starting with the GLB compact crossover.

The M 252 LS builds upon the 1.5-liter M 252 architecture introduced in 2025, featuring targeted upgrades for improved performance, efficiency, and refinement. Mercedes engineered the electric exhaust-gas turbocharger in collaboration with Mercedes-AMG High Performance Powertrains (HPP), the British division responsible for developing and building power units for the Mercedes-AMG Petronas Formula 1 team and its customer teams.

Designed to eliminate traditional turbo lag and provide immediate throttle response across the rev range, the electric motor can spin up the turbocharger independently of exhaust-gas flow. Furthermore, the unit acts as a generator capable of recovering up to 2 kW of energy from the exhaust stream and converting it into electricity. According to a Mercedes-AMG engineer, the system can even be energy-neutral under certain driving conditions, generating enough electricity from waste exhaust energy to power its own electric motor without drawing additional energy from the car's electrical system.

In the M 252 LS, the four-cylinder engine generates 228 horsepower, supplemented by an additional 31 hp from the electric turbocharging system. By comparison, Mercedes also builds the M139l, the most powerful production four-cylinder engine with up to 469 hp in the C63 and GLC63, though slow demand has pushed the automaker toward inline-six engines for its 53-series models.

Making its first appearance in the GLB 250, the new 1.5-liter M 252 LS shaves 0.1 seconds off the 0 to 62 mph (100 km/h) sprint compared to its predecessor. At the same time, it lowers CO2 emissions by approximately 17 percent relative to the outgoing GLB equipped with the larger 2.0-liter M 260 engine. Alongside Porsche, which utilizes electric turbocharging in the 911 GTS and 911 Turbo S, Mercedes is demonstrating that internal combustion engines still have room for technological advancement even as electric vehicles grow in popularity.