So, when you step off the accelerator on a car with an automatic transmission, the ECU has to decide whether it will switch to the tallest ratio to let the car coast and save on gas, or keep the same ratio and engine brake using the intake vacuum. On a traditional automatic, you either use the paddles to keep in the required gear, or on older transmissions use the 3 or 2 position on the column lever.
CVTs have no fixed ratios, and do not need to in order to engine brake. My preferred control would be a small column-mounted stick with 2 or 3 positions that would enable automatic engine braking at varying strengths, kinda like the controls for an electric retarder on big trucks or buses.
