Due in the middle of 2011, the next-gen ML is still largely a matter of speculation. Spy shots of an early prototype, which you can see over at Auto Motor and Sport, reveal a smaller body than the current ML, though the wheelbase appears unchanged.
A few reports have revealed that a diesel-electric hybrid M-Class is in the works, although a petrol-electric hybrid like that shown in the 2007 concept ML450 hybrid is already expected to arrive later this year. A plug-in variant of the ML hybrid is even possible, featuring an 80hp (60kW) electric motor paired with a twin-turbocharged and direct-injected 3.5L V6 and capable of travelling up to 18mi (30kW) on electric power alone is also thought to be in the works.
That plug-in hybrid system will draw on elements from the other hybrid programs within Mercedes, including the S400 powertrain. But other elements, including parts and underpinnings, will be shared more closely across the R-Class successor and G-Class vehicles to help achieve economies of scale while still maintaining separate identities. The chassis underpinning the new SUV is also the same design found in the 2011 Jeep Grand Cherokee, one of the lasting legacies from the now defunct DaimlerChrysler.
The ML’s dominant position as the consumer 4x4 of choice within Mercedes' lineup won't change, though the focus will increasingly be on efficiency rather than performance. Accordingly, European models will likely get a 2.2L four-cylinder diesel engine rated at 204hp (152kW). A V6 diesel rated at 225hp (168kW) and a 333hp (248kW) V6 petrol engine is also thought to be in the plans. The V8 engine will gain direct-injection and twin-turbochargers for the AMG model, which is expected to deliver at least 570hp (425kW).