Which used Citroën C8 MPV should I buy?
Simple - go for a diesel. The petrol 2.0 is cheaper, but it doesn't have the pulling power of the diesels and drinks fuel quicker - likewise the 2.2 petrol.
There are two excellent turbodiesels - a 110bhp 2.0 and a 130bhp 2.2. We prefer the 2.2 for its extra 24lb ft of muscle, and there's only a minimal penalty in fuel consumption. However, it will cost more, so the 2.0 HDI is a good second-best.