When should you downshift an automatic transmission vehicle?

Downshifting an automatic transmission vehicle is particularly important when going down grades. This practice helps to maintain control of the vehicle by using engine braking, which reduces reliance on the brake system. Engine braking occurs when the transmission shifts to a lower gear, allowing the engine to slow the vehicle down naturally without overusing the brakes. This can prevent brake overheating and increase overall safety by maintaining better control.

When descending steep grades, downshifting can keep the vehicle at a safe speed, reducing the risk of brake failure, which can happen if the brakes are applied continuously over long distances. Additionally, it enhances stability by keeping the vehicle within a controllable speed range, thus minimizing the chances of skidding or losing traction.

In contrast, during acceleration or when driving on level terrain, the vehicle is typically in a higher gear for better fuel efficiency and power. Starting from a stop usually involves an automatic transmission engaging the appropriate gear without the need for manual downshifting, as the transmission is designed to do this automatically.