Internal combustion engines are way, way better at propelling cars than any of the electrical whatnot we have come up with. Sadly, oil is terrible for the environment, fraught with political tensions, and getting more and more expensive. Mercedes has one (temporary) solution to this problem in the form of the new B200 Natural Gas Drive. While burning natural gasses still produces carbon emissions, it produces much less than burning oil does; this puts our reckoning at the cold hands of angry ice-caps further away, which is a good thing.
The B200 NGD offers 16% less emissions than the next most efficient B-class while still delivering a respectable 156hp.