[anticrymactic]

Could charging in the ignition be good enough to keep it full? Or a secondary dock at home?

I don't really like the idea of short term key batteries, but it sounds like bmw can improve the current system a lot.

[Hamuko]

There's no ignition in BMWs anymore. Even if you don't go for the full keyless package, the start is still keyless. You just pay extra to have the doors be keyless too.