I'm guessing this is past its usefulness but there are quite a few things which can insulate food. That are cheap. You mentioned "ice" so I'm guessing the challenge is keeping it cold, not hot. Since it sounds like you have an almost infinite ice supply (hotel) the main trick is simply putting the ice in a container and keeping the meltwater from destroying the food (or your car).
A $3 plastic tote from target will hold 40lbs of ice easily and won't leak. Prop the food above the ice (but still inside the tote) so as it melts it doesn't soak everything.
Another idea: many cars have drain holes around the spare tire. If yours has that, fill the whole wheel-well with ice and then put the food on top. Cover with a tarp/blanket and it will stay cold until all the ice melts.
If you are feeling crafty you can built a makeshift (but highly insulated) with rigid insulation foam sold at any big-box hardware store. All you need is some packaging tape and any kind of knife. Cost: about $15 for a super-insulated (R-8) cooler-box (2ft x 1ft x 1 ft) that can keep ice cool for days. Double up the insulation and stagger the seams. This is how we often transport biological field samples and it keeps things cold (or hot) as long as any YETI. It's not bear proof though. Actually, a determined mouse could get in. And it'll shatter if you drop it or sit on it. But it's a super-cheap alternative (to a YETI or similar) and it packs flat until the next time you need it.
