Yes, they do. How well they work is up for debate, though. Most 12V car coolers can only lower the temperature 40ºF below the ambient temperature. That means that on a hot 90ºF day, in a car without the AC running, your food and drinks will be at around 50ºF. That’s not desirable if you want to take a sip of ice-cold water. This is where car refrigerators come in handy. They effectively lower its inside temperature considerably even on the hottest days. For instance, it can be 90ºF outside and your food and drinks will still be kept at 20ºF.