In the car it is in my purse, or my cupholder. Or, it may be in a slot above my stereo. The one my car came with, the CD player died in it, so I bought a replacement and due to slightly different dimensions, there is a newly created storage slot just above it now. Perfect for a CD case, or to slide my phone into.
I also consider what things become projectile in a crash (crashed once when I was in college years ago and the fold down seats in the back flew down and items from my TRUNK ended up in the front floorboard. Lucky for me, they didn't hit me on the way there.
I think in a regular crash, the in-dash slot is great for my phone. And pretty easy to access if i am immobile in my seat after-the-fact. In a roll-over--all bets are off no matter where you put something.
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Oh, and when not in the car, I have a slot/pocket in my purse for it. I am extremely picky when it comes to purse purchases, and I ALWAYS carry my purse wherever I go. My keys and phone stay IN my purse, unless I am using them. If I am driving in the car, my phone goes where I mentioned above... if I am a passenger, it stays in my purse unless I am using it.
I am not one to stick my phone in my pocket or jacket. And I never could quite wrap my head around how my daughter found someone's cell phone in a public bathroom stall... (until reading this thread!).
Before the phone I currently have, I had a clip on my phone, and the instant I was in the car, the phone was clipped to my visor. It was part of the "process" of getting in or out of the car---same as hitting the button to the garage door. You reached up to grab the phone and clip it to the pocket on the purse, just before you pulled the keys from the ignition.