Following previous introductions of their versions of the jointly developed two-mode hybrid system by General Motors and Chrysler, Mercedes-Benz revealed its first use of the drivetrain in the new ML450 Hybrid SUV.
The system combines a 275-hp (205-kW), 258-lb·ft (350 N·m) Atkinson-cycle 3.5-L V6 with a pair of electric motors integrated into the transmission and connected to a 288-volt, 45-kW nickel-metal hydride battery pack provided by Cobasys, LLC.
Total system performance is 335 hp (250 kW) and 381 lb·ft (517 N·m) and Mercedes claims several firsts for its execution of the two-mode technology. Advanced cooling of the battery pack permits battery recovery under high load and high temperature conditions, explained engineer Michael Weiss.
There is also a “traffic jam” driving mode that lets the driver use only electric power, even when the battery charge status is low. For durability reasons, the battery pack is normally kept near the middle of its capacity, said Weiss. And a Power Launch Control lets the ML450 vault off the line using maximum power from both its gas and electric motors for the fastest possible acceleration.
The company lists the ML450’s performance as 7.8 s for 0-60 mph (0-97 km/h) acceleration, 15.8 s quarter-mile acceleration, and a top speed of 131 mph (211 km/h).
“This means that the hybrid powertrain achieves 88% of the power output and 94% of the maximum torque generated by our V8 gasoline engine,” observed Ernst Lieb, President and CEO of Mercedes-Benz USA. “Most importantly, it consumes 47% less fuel,” he continued.
The expected EPA fuel economy ratings are 21 mpg city and 24 mpg highway.
In a brief test drive in Manhattan, the ML450 proved to be well calibrated, with none of the intrusive regenerative braking during stop-and-go driving that is exhibited by some hybrids.