I'm sure that there are plenty of food sources at the portal that are a lot easier and more productive than turning your car into a sardine can.
Seriously though, I doubt that bears are going to be too interested in the scent left by some Ritz cracker crumbs and a three month old spilled pepsi.
I have a kid, so I guarantee that there were crumbs and spills in my car when I parked at the portal. And my car has never been bothered.
I think that bears probably smell all the little smells, but wait for the visual confirmation of an ice chest in the back seat before breaking windows and pealing back sheet metal.
