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It won’t be on sale until this time next year, but BMW has responded to Mercedes-Benz’s unveiling of the S400 BlueHybrid by releasing limited details about its own version of the same drivetrain, the 7-Series ActiveHybrid.

Set to make it’s debut at the Paris motor show, the ActiveHybrid will be BMW’s first true hybrid model. It uses a twin-turbocharged 4.4-litre V...Read the full article

I'm intrigued as to why BMW and Mercedes aren't doing this with their diesel engines. Twin-turbo 4.4l V8 hardly seems an obvious choice, surely starting with the most economical model and making it better would result in the most guilt-free exec limo (if indeed that is the object of this exercise). I'm sure this goes like stink though...

Yeah, it does seem odd. Surely what the world needs more is a 320d hybrid, not a 750?

NiallOswald:

I'm intrigued as to why BMW and Mercedes aren't doing this with their diesel engines. Twin-turbo 4.4l V8 hardly seems an obvious choice, surely starting with the most economical model and making it better would result in the most guilt-free exec limo (if indeed that is the object of this exercise). I'm sure this goes like stink though...

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 I would guess it's because the car is intended for the USA. If you want an economical version of the 7 Series in Europe you can order the 730d. But that's not going to sell so well in a country that doesn't have widespread availability of low sulphur diesel.

I agree that it seems a little odd that it's added to the 4.4l turbocharged v8, rather than the more obvious "economical" 3l six. Maybe it's because their competition over there is the Lexus 450h and 600h. Neither BMW nor Mercedes can currently offer anything similar to the Americans.