I think the part of the brain that's making the routine on-road decisions (checking for obstructions, adjusting speed and position as necessary etc.) doesn't care if you're in a car or on a bike - it just kinda does what it's used to doing. I drive extremely little (so every time I'm in a car it's definitely a new and unusual situation for me making me vigilant and sometimes unnerved), but even so I occasionally still find myself thinking "Parked car ahead, oh not a problem, there is room left in the lane, so I don't have to chang lanes... um, wait... I'm in a car, the car won't fit there."

On the other hand, I do have a zero-tolerance policy on rolling stop signs when in a car. That comes naturally anyway, since you can't see anything in that freaking metal cage, and you really do need to stop a lot of the times to be certain that the intersection is clear. Well, at least I do.