I had a 40 litre Engel for a few years, never missed a beat and used very little power. Next I bought a Waeco CF25, never missed a beat and used very little power. I bought a Stirling from Aldi the other week, it also appears to use very little power and I assume it will be every bit as good as the Waeco CF25 because it is a rebadged Waeco CF40.
Still believe that when it comes to portable fridges, Engel is the bench mark. Unfortunately, the Engel wouldn't fit in our ASX so we sold it and bought the CF25. When I saw the Stirling on sale for $499 I grabbed one and retired the CF25. The Stirling is the same height and length of the CF25, just a little wider.