I was very scepticle about this cooler as I have owned multiple thermoelectic coolers in the past. I thought "there is no way this thing can freeze off of a 12v cigarette plug". I purchased for a family vacation to Florida and was hoping it would at least keep out drinks and such cold if I set it to the lowest temperature. 3 hours into our trip we made a stop for a restroom break and a drink, and to my surprise there was slushy ice in our bottled water. I decided to leave it at the same temp until our next stop and see what would happen. BIG MISTAKE... our water was frozen to the point that we had to wait and let the water thaw out in order to drink it. I adjusted the temp to 35 and the cooler maintained that temp for 10 days with only a few degrees varying from time to time. I would buy this cooler over and over again, Thanks VEVOR!!