More than half of motorists act more aggressively while driving than they would in person, according to new research.
Once behind the wheel, many motorists admitted shouting and swearing at strangers, but said they would not do so face to face.
A survey of more than 2,000 adult motorists found that:
31% swore at strangers, but only 12% would do so in person
26% shout at others, but just 12% would do so in person
The survey also found that a third of drivers (33%) have beeped their horn aggressively and 11% have deliberately tailgated another vehicle.
The top excuses for aggression behind the wheel, the survey found, include the belief that the other person probably cannot hear them, and feeling protected inside their car.
"Psychologists have known for years that cornered animals behave aggressively and being trapped in a metal box in heavy traffic can change even the most mild-mannered of drivers," Neil Greig, from the Institute of Advanced Motorists, said.
Steve Barrett, from Churchill Car Insurance, which commissioned the survey, said motorists should try to be calm when face with aggressive behaviour.
"Remember that these frustrations often blow over as quickly as they arose, so it's best not to give them any oxygen to escalate," he said.
Psychologist Donna Dawson said the key to avoiding aggression is not to over-react.
"If we became angry at every perceived injustice that occurred to us on the road we would damage our mental and physical health and probably end up in an accident," she said.
"The only way to make driving safe and more tolerable on our congested roads is to show each other patience and consideration."