NZ drivers are raging bulls

New Zealand drivers are more prone to road rage than those in the United Kingdom, but we're not nearly as bad as the Americans, according to an official study.

Police say it is hard to tell exactly how many road-rage incidents happen each year.

There are no official statistics for road rage as it is not a specific offence.

That means those who commit road rage are often prosecuted for assault and other offences, police say.

In a 2003 study, Massey University's Dr Mark Sullman found police presence, traffic obstructions, illegal driving, hostile gestures and discourteous driving to be the main causes of road rage.

There have been numerous high-profile cases of road rage in New Zealand in the past few years.

In July 2007, possum trapper Dae Van Der Maazen was sentenced to two years' jail for slashing another man twice in the stomach after a road rage incident in Papamoa.

In October 2006, George Frires was sentenced to two years' jail after an unprovoked attack on an 81-year-old woman in Tauranga. The assault left the elderly woman with a broken nose, two broken eye sockets and a fractured palate.