yup, think it's electric pre-heater in all bmws nowadays, if there was no help from an extra heater the engine would have seriously problem getting warm and there would defenitely be cold as hell in the car. That's the "problem" with modern deisels, so efficient that almost no energy is wasted generating heat. Anyways the electric heater works and it does not drain the battery. I guess they solved that problem. I guess the generator does a good job... it feels like the engine-braking is pretty massive when driving away on a cold morning, rolling down a hill in gear, so maybe the generator puts a pretty heavy load on the engine. I don't know. All I know is the engineers were smart enough to come up with a working solution. Don't think bmw would sell diesel-cars if all of them got stranded during winters due to battery-drain (at least the short-trip drivers).
Anyways I wouldn't be scared to go for diesel, untill there is some hard facts provided. No offense but a rumour of someone selling alot of crankcase-ventilations parts to bmw diesel-owners isn't enough to convince me.