Peugeot ES9

PSA's 3.0 V6 petrol — in the 407 and the C5, and in the large Peugeots and Citroëns before them.

It is the flagship engine of a range that is otherwise four-cylinder, and that is most of what makes it awkward: it is rare enough that specialist experience is thin, and it sits in engine bays designed around something smaller.

Access is the practical constraint on almost every job. The rear bank is against the bulkhead, and work that is an hour on the front bank is a day on the back — which changes what is worth doing preventively rather than reactively.

It is belt-driven and it is an interference design, and the belt change is exactly the job the access problem describes. On a car of this age with unknown history it is the decision that determines whether the car is worth keeping.

Its running complaints are ordinary: coil packs, a carboned throttle body, and variable valve timing solenoids that respond to clean oil. The EW four-cylinder page covers the engines most of these cars actually have, and its results do not transfer here.