Toyota K120 (Direct Shift-CVT)

Toyota's CVT for the TNGA cars — the Corolla, Camry, RAV4, Yaris, Avalon, Venza and Corolla Cross, and the Lexus ES and UX.

It is not an ordinary CVT, and the difference is mechanical rather than a matter of tuning: it has a real first gear. A conventional CVT pulls away on its belt, at the widest, least efficient and most heavily loaded ratio it ever runs. This one launches on a fixed gear and hands over to the belt at about 30 km/h, which is why it feels normal from rest where CVTs are usually at their worst.

That single fact redirects the commonest diagnosis on this transmission. A shudder or a hesitation only from a standstill is the launch gear and its clutch handing over, not belt slip; a slip or a flare at speed, under load, with the engine rising and the car not is the belt and pulleys. They are different faults in different parts, and treating a launch-gear symptom as belt wear condemns a transmission that is fine.

The recurring service theme is fluid and heat. Toyota's CVT fluid is specific, a CVT's belt clamping depends entirely on hydraulic pressure, and a fluid that has aged loses clamping before it loses anything else — which is felt as a slip under acceleration long before any noise. Towing and sustained hills are what age it.

The engine braking a driver expects is largely simulated. A CVT holding a "gear" on a descent is the control unit choosing a ratio; there is nothing to grind and nothing wearing unusually when it does.