I thought he wanted a dual zone fridge freezer. Lots mentioned here don't have a dual zone - or do they. Most seem to have a fridge freezer that can be one thing at a time, not both.
I have a Waeco 50l Dual Zone. It works well set at -10 while camped and ten while we drive I set it to -18. It will never get down to -18 but close. Best I have got is -16. They use a bit of power hence running it flat out while we drive then notching it back a few degrees while camped.