2009 Mercedes-Benz S-Class Brings Hybrid Power and Advanced Safety
The 2009 S-Class introduces the S 400 HYBRID with a lithium-ion battery, improved efficiency across the range, and a suite of new driver assistance systems.
Mercedes-Benz launched the 2009 S-Class with a major focus on efficiency and safety, headlined by the S 400 HYBRID, the first production car to use a lithium-ion battery in its hybrid system. The new S-Class arrived four years after the debut of the W221 generation and aimed to reinforce its position as the benchmark for luxury saloons.
S 400 HYBRID: First of its Kind
The S 400 HYBRID stood out as the world’s first series-production hybrid to use a lithium-ion battery, a step forward from the nickel-metal hydride units seen in earlier hybrids. This setup paired a 3.5-litre V6 petrol engine producing 279hp with a 20hp electric motor, resulting in a combined system designed for both efficiency and smooth performance. The hybrid drive included automatic start-stop and energy recuperation, with the lithium-ion battery compact enough to fit in the engine bay without sacrificing boot space or cabin comfort.
Mercedes claimed the S 400 HYBRID could achieve 7.9 litres per 100km and emit just 186g/km of CO2, figures that set a new standard for petrol-powered luxury saloons at the time. The electric motor contributed 160Nm of torque from standstill, smoothing low-speed acceleration and supporting the petrol engine during overtaking. The hybrid system was integrated with a specially calibrated version of the seven-speed 7G-TRONIC automatic gearbox.
Efficiency Gains Across the Range
Beyond the S 400 HYBRID, the 2009 S-Class engine line-up included eight further petrol and diesel units. Mercedes introduced BlueEFFICIENCY measures across the range, such as improved aerodynamics, demand-controlled fuel pumps, and optimised gearshift programming. The S 350 BlueEFFICIENCY diesel, for example, returned an average of 7.6 litres per 100km, placing it among the most economical luxury diesels on the market at the time.
- Two diesel engines and six petrol engines available.
- All engines received updates for lower fuel consumption and emissions.
- BlueEFFICIENCY package included aerodynamic tweaks and energy-saving features.
Advanced Safety and Driver Assistance
The 2009 S-Class introduced a suite of new safety and driver assistance systems. Adaptive Highbeam Assist adjusted headlight range to avoid dazzling other drivers, while Lane Keeping Assist and Speed Limit Assist used cameras to monitor road markings and signs. Night View Assist PLUS improved on the earlier system with better pedestrian detection. Mercedes also added ATTENTION ASSIST to monitor driver drowsiness and automatic crosswind stabilisation for improved stability in challenging conditions.
These features reflected Mercedes’ strategy to position the S-Class as a technological leader, with many of these systems later filtering down to other models in the range. The focus on active safety and driver support complemented the S-Class’s established reputation for occupant protection and comfort.
Sales and Market Impact
By the time the 2009 model arrived, Mercedes had sold 270,000 units of the W221 S-Class since its 2005 launch. The S-Class continued to outsell rivals in the luxury saloon segment, maintaining its position as the flagship for Mercedes-Benz and a reference point for innovation in the sector.
