Gents,
I may be wrong, and I usually am according to "someone I live with", but we're confusing S with O in some replies. The original post was concerning an S gauger and some replies talked about Baby Madison and "semi-scale" cars. Neither exists in S, although input from our brother O gaugers is always welcome. The cars I have (in S) are all painted, not colored plastic.
As far as removing the paint the Lionel uses on their items, I've found it to be quite tough stuff. I'd recommend what others like gunrunnerjohn have recommended. That is, simply get the lettering off and apply just enough paint to cover what the factory applied so as not to further obliterate any cast-in details. Lionel has some nicely done molded details like rivets in their offerings, but to actually go to the trouble to COMPLETELY remove factory paint to see rivets more clearly would put us dangerously close to the dreaded category of those who count them! 
BTW, I too have a project in mind for "one of these days" which also involves a repaint of PE cars, but I plan on simply removing the lettering and painting over the factory PE colors with Pullman Green.
