The 3 things that are likely to kill a fish on a long travel are temperature, lack of oxygen, and ammonia.
In a few hours there will not be enough ammonia to kill a hardy fish like a poly, and if you add some prime it could last even longer.
As long as you don't cool your car super cold the poly will be fine temperature wise.
As for oxygen I have never had any problems keeping fish for long times in a bucket, and I don't feel you need a bubbler as poly's are air breathers, so it doesn't matter i the oxygen level in the water drops.