Haven't tried that one but I'd be sceptical - never found one that works more than a day. You can get one that charges from a car cigarette socket - I have one and it's great as long as you're driving at least half an hour or so a day. Otherwise take long-life milk, tinned food and you might manage cheese OK for 2-3 days if you can keep it in the shade or use bucket placed in a nearby stream (but rat-proof)
Yes we have one and yes it can last 5 days - but you do have to take care of it - we add more ice every couple of days and it works a treat. Also don't put anything in it that's not already cold (sounds basic but you wouldn't believe the men I've seen putting their warm beer in and expecting the rest of the stuff to stay just as cold.....)
No it doesnt and the tests arent stringent enough and assume you have a box in a hot tent that could be 30 degrees plus then it wouldnt last. Plus taking the lid off to remove produce isnt going to help.
I have a polar??? its on wheels very useful and great if you pop frozen foods in there - makes the box stay cooler.
After a couple of days the icepacks defrost but surely you'll be close to the odd shop to buy more and many sites have freezers to refreeze your packs?
It will be fine to keep meat in for a couple of days but deli foods just be careful.
I have the Coleman Xtreme and it works well for trips of 4/5 days. I pre-cool it for a couple of days before we go with frozen bottles of water and, once filled, I put tea towels or hand towels over the cold stuff for insulation if there is space left. The idea is to have no free space in it once the lid is shut. I do try and refreeze the blocks as and when I can while away.
But, the main consideration is do you have space in your car? They are HUGE!