I let three people drive it.....Me, Myself and I.
Part of it is "fit". I pulled the seat tracks out and bolted it to the floor to better accommodate my 6'3" height. Secondly, my insurance company won't allow it.
The other part is just sure, plain "Sorry, but I just can't trust someone else to let it get away from them." It's not like getting into my previous daily drivers (Z-28s, Corvettes, etc.). I let others drive those ALL THE TIME. Different feel, different coverage and less prone to really swap ends on you.
I do miss my wife driving the previous cars though. Something about a woman barking 2nd gear got me going....
-Dean