Yes I do. Never know what can happen. It's also good if I want to stop by the range when I am out. Theres nothing illegal about leaving ammo in your car here.
The bridge is out,the road is flooded, the riot is between you and home, etc., what ever the reason, you might (possibly) be forced to spend some time with just what's on your person, and in your vehicle.
That happen to me, I was stuck in traffic for 4 hours once..... Then the car could over heat, break down then get towed to the bad side of town.