Important questions to facilitate my purchase decision !! Audi A6

Hello people !! I want to get a new car in the next few months ! Because of my dog only a combo comes into question for me ! It should be the A6 4B ! Let’s see what happens ! Now my questions about motorization for consumption and the arising defects or wear and tear I have to pay attention to when buying ! For me come into question : 1 – the 1.8T with 150 hp 2 – 2.4 l V6 with 165 3 – 2.8 l V6 193 I would be happy about personal experiences , these could make the purchase decision easier for me ! Already in advance thanks for the answers ! MfG Maik