I am amongst those guys who always used to complain that women unnecessarily lug a heavy handbag around which is stuffed with junk. However recently I have noticed that guys are no better either. Just open the boot (and not just glove box area) and be amazed by the quantity and variety of stuff they carry around.
Running shoes, towel, change of clothes…. This I saw in the back seat of a guy who swears that he has not been to the gym in over a month.
An empty: Mini-fridge. (An insulated cooler is more common) I would love a drink on the road, but what use it would be if you have not stocked it.
Paint cans, dent removal kit, a tool kit that would rival the one owned by your mechanic. I wonder how often you would stop at the traffic light to repair your car (a bit of context, most Indians go to a mechanic even for a simple flat tire)
Items in the ToDo list which have been lying untouched for months.
CDS, dvds, combs, deodorants, etc. and all the other junk you can think of.
I guess what really happens is that one sees a huge personal storage space and over time we find stuff to fill it.