The state diagram is drawn by considering the concurrency property of the aggregate objects that make up the car object i.e each aggregate object has a state of its own. Below is a sample state diagram for a Car object -

Below is the state diagram for Ignition System -

State Diagram - Transmission

State Diagram - Accelerator

State Diagram - Brake

Below is the state diagram for Ignition System -
State Diagram - Transmission
State Diagram - Accelerator
State Diagram - Brake