Ulysses, how does my transmission let me know what I need to do....(I
have an automatic if it matters)

Well this complicates things a bit... So if I stay under 35 and just
do city driving stay out of O/D
So concretly O/D should really be used when I am on the interstate, I
guess.

I realize these must be mega-newbie questions, and I must confess that
I am now more confused than ever....