The X5 does not have a smart passenger airbag, I think. No sensors. When you start the car, along with most dash lights, it will illuminate to check the status. It will go off, unless you have a problem, which is when the car would not be safe to drive, so take it to the dealer asap. Airbag issue could = 1. airbag won't work. 2. It will inflate improperly. 3. or something else really bad. Not good!
Your benz has a passenger sensing system.
Hope this helps!
