The Vehicons are Megatron's personal army, a legion of military Transformers that allowed him to conquer planet Cybertron and protect his one-robot empire from all threats. They pack lots of firepower and travel and attack en masse.
The overwhelming majority of Vehicons are unliving drones without innate sentience or spark. Each Vehicon drone is usually controlled either directly by Megatron, or by a single sentient Vehicon general of the same (or similar) design. After the loss of Tankor and Jetstorm, their respective drones are apparently controlled by other generals.
Vehicon drones are generally blindly obedient, with no sense of self-preservation. On rare occasions, various drones have appeared to use emotive body language, shaking in apparent fear or pleading (wordlessly) not to be shot. On one occasion a Tank Drone was seen to vocalize with Tankor's voice.