We have a 110L Waeco. It is a great fridge/freezer.
You can never go to big if you have the room I think (Does that make sense) fridge in car!!
I have two kids so on big trips I remove the single second row seat from my cruiser and put the Waeco there.
It sit on a custom made cradle bolted to the seat mounts then ratchet straps hold it to floor anchors (Don't want it coming loose).
On small trips it goes in the back behind the cargo barrier.
I had to run 6mm cable for it to work properly and I fit Clipsal 32v two pin plugs for good connection.
It does not drain the battery that fast but it does like good clean power.
It will freeze stuff you pick up on the trip and keep the coke cold to add to my rum at the end of the day.
That's what it is all about
Mark