Normally, giant four-door luxury sedans aren’t considered very green. That changed when Lexus unveiled the LS 600h, which taught rich people that they could still have a big honkin’ sedan and feel good about themselves at the same time. Not wanting to be left behind, the BMW 7 Series ActiveHybrid Concept was unveiled at the 2008 L.A. Auto Show. Based on the new BMW 7 Series that goes on sale early next year, the Active Hybrid uses a 20kW electric motor to augment starts, resulting in roughly 15 percent better fuel economy. OK, that won’t change the world by itself, but it is definitely a step in the right direction.