What is preconditioning a car for smog test The tech said I need to drive the pick-up around more 30-40 miles since had been sitting awhile.?

The mechanic is correct. Preconditioning a car for a smog test, especially one that's been sitting for a while, means driving it to ensure the engine's emissions control systems are operating correctly and that the catalytic converter reaches optimal operating temperature.

Sitting for extended periods can cause the catalytic converter to become less efficient and produce higher emissions than normal. Driving the vehicle for 30-40 miles allows the engine to warm up completely and the catalytic converter to function at its peak, giving a more accurate reading during the smog test. The goal is to get a representative reading of the emissions under typical driving conditions, not a "cold start" reading.