If the human autonomic nervous system were compared with a car, the nervous system functions like the car's accelerator, and the nervous system functions like the car's brake.

If the human autonomic nervous system were compared with a car, the sympathetic nervous system functions like the car's accelerator, and the parasympathetic nervous system functions like the car's brake.

Explanation:

These two systems make up the autonomic nervous system (ANS) which are both involuntary movements. The sympathetic nervous system (SNS) kicks into action when the body is under threat ie. 'fight or flight' both very fast movements thus has short, but fast neuron pathways. Causing the body to speed up and increase blood flow to only essential oragns.

Next is the parasympathetic nervous system (PSN) and this system maintains homeostatis ie. 'rest and digest' thus slowing down the SNS resulting in longer pathways and much narrower systems.

all the above is what i would say