If I had a choice between storing a folder in a closet corner or in a vehicle, I'd choose the closet corner every time.
Why? If anyone sees you loading or unloading your folder from your vehicle, that alone would be reason enough to break in and take it. Doesn't matter if it's not in view, covered, etc. Much more difficult to break into someone's home. Given the choice between a home burglary and a vehicle burglary, which do you think a burgler would choose?