One of the pamphlets that came with the FEH explained that noise you hear when you open the door (it also happens when you unlock the car with the key fob). I *think* it mentioned it had something to do with pressurizing an element of the regenerative braking system.

I didn't know the nav computer comes on when the ignition is in the 'accy' position. My FEH doesn't have the nav computer. I factory ordered mine and opted out of the nav computer option. It'd be really nice for out of town trips, but I don't tend to take out of town trips. In town I figure I know my way around and wouldn't probably rarely use it.