When I had a pickup, the Rem1100 was always in a scabbard on the inner roof of the cap. But there is nowhere in my present ride that I can use to secure the shotgun, especially with two small children in the passenger compartment to deal with. The CZ97B is about as big of a package as I can safely conceal in the vehicle, so that's what I use it for.
And I'd love to carry my SW 629 Mountain Gun, but that's kinda tough to conceal when wearing dress trousers, a short-sleve shirt, and no jacket. The mousegun is all I can do, and I figger it's better than throwing rocks.