The findings, taken from more than 2,000 motorists, were released in conjunction with Stress Awareness Day last week, with the motoring organisation urging drivers to remain calm behind the wheel.
Drivers staying in the middle lane, not indicating, speeding in built-up areas, cutting lanes and failing to give way to oncoming traffic are also high in the annoyance stakes.
Green Flag spokesman Nigel Charlesworth said: 'With daily pressures like the school run, getting to work on time and rushing to meetings, all in an ever-growing tide of traffic, motorists are regularly put under immense strain.
'Anxiety, tiredness, muscle tension and poor concentration are all symptoms of stress, none of which are conducive to safe driving. Actual road rage attacks are rare, but stress is common.'