In March, Automotive News reported that Mercedes-Benz will go 100-percent hybrid with its next-generation S-Class lineup in America. In other words, you won’t be able to buy an S-Class that doesn’t have a hybrid gas-electric system. If the story proves true, then it makes sense that Mercedes will extend the line to include a plug-in. The idea is already on the table, with the Mercedes S500 Plug-in Hybrid concept—shown at the 2009 Frankfurt Motor Show.

The so-called Vision S500 Plug-in Hybrid can drive for about 18 miles solely on electricity. In the new European test cycle, that would produce a rating of about 75 mpg or 74 grams of CO2 per kilometer. Think of the possibility of a 70+ mpg S-Class sedan with all the comfort, safety and luxury of a top-of-the-line Mercedes. Of course, such a vehicle is likely to cost north of $90,000.

The drive system consists of a V6 gas engine with direct injection system and a 44 kW - 60 horsepower hybrid system with a 10 kWh lithium-ion battery. An additional clutch decouples the hybrid system from the combustion engine—maximizing efficiency during pure electric driving. The Vision S 500 Plug-in hybrid will be plenty fast—accelerating from 0-to-60 in about 5 seconds.

The hybrid module's design does not differ much from the compact, disc-shaped 15-kW electric motor of the S400 Hybrid, even though it is three times as powerful. As a result, the hybrid module can be incorporated into the housing of the seven-speed automatic transmission, meaning no compromise to the S‑Class's interior space. The battery is located behind the rear seats in the trunk. The lithium-ion battery's location above the rear axle ensures that the vehicle has a balanced weight distribution and that it’s protected in case of a crash.

Dream Car or Distant Dream?

The big question, of course, is if and when Mercedes would produce such a vehicle. "We already have all the key technology we need for such a dream car, which is why I see it being included in the next generation of the S‑Class,” said Dr. Thomas Weber, who is responsible for Mercedes car development. "Although it will take some time before this model can go into series production, our engineers will be working full steam to carry out the necessary integration measures.”