Re: what does 'outside' mean when talking about the 'skin effect'?

Good Question.
The phenomenon of skin effect indeed means that the current will travel 
along the outer surface of the car body.  The key thing to realize here 
is 'outer':  the lightning current will travel along the hood and fenders 
to get to the ground point.  In theory, then, the current will not be 
anywhere near the curvature of the windshield so that if you were to touch 
the inside body you *ought* to be safe, although this is *NOT* 
recommended. When considering lightning, there are other things to 
consider called step potentials, where the current thru the car body is so 
large that there would be a significant voltage difference between one 
side of your fingertip and the other, so you could definitely get hurt 
even though skin effect is working:  DON'T try it.  Making things even 
more dangerous still is the fact that you might be grounded to one side of 
the car body and touch the curvature of the body at the windshield;  then 
a very large voltage will develop across your body and you'll get zapped.  
If I were in a car during a lightning storm I'd sit in the center of my 
seat with my hands folded in my lap, but I'd still be nervous.