For my money, the real automotive argument booster is more existential. When we're in the car, our psyche becomes unsettled. We're neither here nor there. We become "in-between" beings, our lives stripped of authenticity and meaning by a transient state.
For passengers, the existential angst is more profound. With no wheel to steer nor pedals to rev, we lose what it is that makes us conscious beings - the capacity for independent action and responsibility. No wonder we get scratchy.
But, hey, let's not argue about it.
The top 10 causes of in-car arguments, according to AAPopulus' survey
1. Knowing the way to go
2. Driving too fast
3. Not asking for directions
4. Noisy children
5. Shouting at other drivers
6. Temperature in the car
7. Not agreeing on where to eat
8. Not agreeing on what to listen to
9. Topic of conversation
10. Driving too slowly