When is the Torque Converter typically applied in a vehicle?

The torque converter plays a crucial role in a vehicle's automatic transmission system by allowing the engine to run at a different speed than the transmission. It typically engages under several conditions to optimize performance and efficiency.

When combined, the conditions mentioned in the options illustrate when the torque converter is beneficial. At speeds above 35 mph, the torque converter can efficiently lock up to reduce slip and improve fuel economy. Engaging it in 3rd gear or higher allows for better power transfer during highway speeds, where maximum efficiency is paramount. Moreover, the torque converter often requires the engine to reach a certain operating temperature, generally around 150 degrees Fahrenheit, to ensure optimal performance and prevent damage due to cold fluid.

Each of these individual conditions plays a part in how and when the torque converter operates, making "all of the above" the correct choice, as it accurately encompasses the various scenarios under which the torque converter is applied. This comprehensive understanding is fundamental for those studying advanced engine performance, as it highlights the torque converter's role in enhancing overall vehicle efficiency and functionality across different driving conditions.