Toyota 2NZ-FE

Toyota's 1.3 — in three generations of Corolla, three of Yaris, and the Scion xB.

It is one of the most numerous small engines on the road and its reputation is entirely earned: chain-driven, port-injected, all-aluminium, and very hard to kill. Most of what brings one in is not the engine.

Its two recurring complaints are cheap. A rough idle or a stall when the throttle closes is usually carbon in the throttle body or a tired idle control, not the coil packs; and the coolant temperature sensor skews fuelling as it ages, which shows as poor economy and a hesitant cold start rather than as a temperature complaint.

The 1NZ-FE 1.5 beside it is the same family and shares nearly everything, so results for one usually apply to the other — and the 1NZ-FXE in the Prius does not, because it runs the Atkinson cycle inside a hybrid control strategy.

At very high mileage the oil control rings can stick, which reads as consumption without smoke. It responds to a solvent soak more often than it needs a rebuild, and on a car of this value that distinction decides whether it is worth repairing.