Hyundai D7UF1 (7DCT)

Hyundai's dry seven-speed dual-clutch — in the Elantra, Kona, Sonata, Tucson and Veloster, and the Kia equivalents.

Dry is the word that matters, and it predicts the complaint. The clutches run in air rather than oil, so there is nothing to carry heat away, and the gearbox is at its least happy exactly where a torque-converter automatic is most comfortable: creeping in traffic, and holding station on a hill.

The symptom people report is a judder or a hesitation from rest, sometimes with a smell, and it is the clutch slipping against the whole weight of the car. Holding the car on the throttle on an incline is what causes it — the brake and the hill-hold cost nothing and are the single most effective thing an owner can do for one of these.

A clutch actuator fault presents completely differently: a refusal to select, a limp mode, a warning light, and no judder at all. Those are two different repairs and the tell is whether anything was ever wrong with how it pulled away.

It is not the D8LF1. Hyundai's eight-speed dual-clutch is a wet unit with its clutches in oil, and it does not have this failure mode — which is precisely why it exists.