I have the 60-liter Engel, about 2 cubic feet. Ran it for 5 months this summer in the back of the Subaru and on shore power when convenient. I upgraded the car battery to a ~65aH deep cycle and put 70 watts of solar on the roof rack. Worked beautifully. The fridge does have a tiny fan that kicks on if it needs more ventilation. Overall, completely satisfied with this fridge. It takes about 2.88 amps when it is cycled on. Car alternator quickly tops off the battery whenever we drive.