Mercedes plans to sell the ML and subsequent Hybrid-powered SUVs only in the U.S.
Next Monday, Mercedes-Benz will officially launch the ML450 Hybrid, the first European marque full Hybrid vehicle to be offered in the U.S.
It is based on the technology developed by General Motors for its dual-mode Hybrid models, which the company subsequently licensed to BMW, Chrysler and Mercedes, all of whom were and are desperately behind in the Hybrid technology race long dominated by Toyota and Lexus.
The Alabama-built ML450 Hybrid joins the S400 Hybrid, which cannot run on electricity alone, and existing “BlueTec” diesel models in its growing portfolio of, relatively, fuel-efficient vehicles.
Mercedes plans to sell the ML and subsequent Hybrid-powered SUVs only in the U.S., global marketing chief Klaus Meier told TDB. The technology is meant to supplement, rather than replace Mercedes’ diesel offerings, which currently account for about 20% of its SUV sales, in the U.S.
ML450 Hybrid will be offered as part of a special lease only option (no purchase allowed!) for a lease price of $659 per month for 36 months and $549 per month for 60 months. A down payment of $5,200 or $5,000, respectively, is required.
A Mercedes spokesperson told us that it is too early to say what will happen to the vehicles at the end of the lease period, and whether they or later production models will ultimately be available for sale.
Readers may recall the huge controversy around Saturn’s lease only EV1 electric cars at GM, which to the outrage of happy owners were taken back and shredded at the end of their leases, in spite of pleas from the owners to buy them.
Whether this is lawyer-generated problem at Mercedes, as it was at GM, or Daimler’s doubts about the life and performance of the ML’s nickel metal hydride batteries, or an attempt to limit the volume of what most assuredly is a large loss-making vehicle, among other possibilities that I haven’t thought of, I’ll leave as open questions.
Mercedes is marketing the ML Hybrid as having V8-like power with four-cylinder fuel economy. Although, Mercedes provided data show that at 7.8 seconds zero-to-60 mph acceleration time, the Hybrid is a full 2.2 seconds slower than the V8. And at 5,000 pounds rated towing capacity, it has 2,200 pounds less capability. I have not driven the SUV but look forward to doing so.
To accelerate to 60 mph in ten seconds, the ML450 Hybrid uses two electric motors and a 275 horsepower V6 gasoline engine. They work together to provide fuel economy of ratings 21 miles per gallon around town and 24 mpg on the highway. The V8 is rated at 13/18 mpg. The non-hybrid V6, 16/21 mpg, and this V6 also has the 7,200 pound towing rating of the V8 engine.
The 3.5-liter V6 engine is optimized via what Mercedes calls an Atkinson cycle, although it — like other Hybrid “Atkinson” applications — is really a modified 4-stroke (Otto cycle) engine, where the compression stroke is shorter than intake and expansion strokes, thereby increasing fuel economy — but at a cost of a reduced specific output.
That’s where the two electric motors and the control electronics of the ML450 Hybrid come in. The instant torque that the electric motors provide can make up for the engine power deficit.
Integrated within the modified automatic transmission, each electric motor serves a distinct purpose. Dedicated to pulling away under electric power, one motor on the transmission output shaft generates 80 horsepower and — more importantly for the driver and launch performance in what is a heavy vehicle at 5,247 pounds — 192 pound-feet of torque.
The second electric motor, located closer to the V6 engine, is set up specifically for acceleration and is rated at 83 horsepower and 173 pound-feet of torque.
The V6 engine works with both electric motors when full power is needed, so the Hybrid has a total system performance of 335 horsepower and 381 pound-feet of torque.
EPA ratings say the ML 450 can produce up to 46% better fuel economy than a comparable V8-powered ML550 model. Your mileage, depending on driving style and traffic conditions, may vary. However, this is a genuine efficiency achievement in this class of vehicle.
The electric motors are powered by a liquid-cooled, 288-volt nickel-metal-hydride battery that’s enclosed under the rear cargo floor. Mercedes claims the ML Hybrid has the same interior room, convenience and safety features as other M-Class vehicles.
A computer controls the Hybrid system, recalculating the best operating mode 160 times a second. Capable of up to 50 million calculations per second, the system works to maintain an” ideal balance” between fuel economy and performance. (Soon cars will be made that won’t require your input at all.)
During parking and low-speed operation, the ML450 Hybrid runs on the electric drive only. The ML450 Hybrid can drive solely on electric power for short distances to a maximum speed of 34 mph. On hard acceleration, the gasoline engine is started automatically, and it works “seamlessly” with the two electric motors for “excellent” performance. The system includes a start-stop function that turns off the gasoline engine — for example, when coasting up to a red light — and re-starts it during acceleration.
During braking and coasting, the electric motor acts as a generator, slowing the SUV and converting kinetic to chemical energy. Under heavy braking, the vehicle’s conventional brakes also come into play. Recovered energy is stored in the battery and re-used whenever the SUV runs only on the electric motors.