Ever read your owner's manual? It says your passenger must sit primly and properly. Really. Imagine your grandmother sitting with her hands neatly clasped in her lap. Okay, that's an exaggeration, your hands don't need to be clasped. They can rest on top of your thighs. I get a kick out of telling my passengers that if they sit with their arm out the window, or even on the door's armrest, that arm can be FORCEFULLY RIPPED CLEAN OFF THEIR BODY!!!
In case anyone doubts my statement, in MY "2004 Forester Owner's Manual" it states, on page 1-64,
"WARNING Do not rest your arm on either front door or its internal trim. It could be injured in the event of SRS side airbag deployment."
Furthermore, directly above the warning is a picture warning against sitting the way 99% of my passengers sit 99% or the time. (See also page
1-63.)
Also, on page 1-66 is a picture of a person sitting in the recommended position. I don't know what the passenger is doing with his hands, but let's just say, if my mother ever caught me with my hands there, she would have made me go to confession.
Anyway, I'm not a passenger too much when I'm driving, but I think the same thing applies to the driver's side, in a mirror image sort of fashion. If that's the case, I think it won't be too long before my arm is FORCEFULLY RIPPED CLEAN OFF MY BODY!!!