They are fast, female and ferocious. Women are driving faster and being convicted more often for speeding and dangerous driving than ever before. The largest study of its kind has concluded that women drivers are as likely to indulge in horn-honking, tailgating, risky overtaking, speeding and making rude gestures as their male counterparts.

It’s not just because cars are faster or more women are on the road, it is because they are as aggressive as men. The study by a team of psychologists in Florida looked at the driving behaviour of 400 twentysomethings and late teens in America and Japan and measured their levels of aggression. On almost every measure young women were equal to or surpassed men.

The study, due to be published shortly in the American scientific press, is loaded with psychometric jargon but its implications are inescapable. Women, it found, exhibited high levels of hostility, sensation seeking, susceptibility to boredom, and competitiveness. The behaviour of the American women appeared to be fuelled by hostility (“I’m in a hurry. Move it or lose it,” was the typical attitude).

John Houston, a psychology professor and one of the authors of the report, says the outcome of the research reflects women’s changing social roles. “We need to recognise that male drivers aren’t necessarily the biggest threat on the road,” he says. “Women don’t seem to be following the rules any more. They may have been more cautious drivers in the past, but that no longer holds. We were very surprised by our findings.”

What is true for women drivers in America and Japan does not necessarily hold in Britain. Insurance companies, which count the cost of accidents, say women in this country are much safer behind the wheel than men. However, they warn the gender gap is closing.

The latest available Home Office statistics show British women account for an increasing share of nearly all types of traffic conviction — especially speeding. In six years from 1996 to 2002 the proportion of women convicted for speeding rose by more than half to 17% of the national total of 124,600. An increased proportion of women were also convicted for drink-driving, driving without insurance, neglect of traffic signs and pedestrian rights, as well as parking offences.

Helen Parker, a 26-year-old marketing executive from south London, admits she drives her Audi cabriolet too fast and swears like a van driver. She has penalty points for doing 85mph on a motorway. “I drive a male colleague in to work every day, and he is always appalled by my behaviour,” she says. “I like to drive fast and I hate it when people get in my way. I wouldn’t like my mother to hear the language I use.”

Houston says women like Parker are the new “fast females”. “We know that women don’t like getting into conflict situations that can escalate, but they obviously feel safe and empowered in their cars and like the thrill and power of zooming along at a high speed.

“This is linked with women’s changing social roles and greater independence. Driving is an extension of the working day.”

Other experts say the reasons may not just be aggressiveness. Andrew Howard, the head of road safety at the AA Motoring Trust, says speed cameras are catching fast women who previously got away with it.

“A greater percentage of the people being caught by cameras are women, because cameras are indiscriminate,” he says. “Women can’t flutter their eyelashes at a speed camera. It used to be that policemen would pull over only the worst offenders, who all tended to be men. Now, if you go at 36mph the camera will get you.”

Nicola Archer, 41, a consultant surgeon at a London hospital, believes she is driven not by thrill-seeking so much as stress.

She was cautioned for speeding by an officer who declared: “Madam, we’ve pulled you over not because you were going over the speed limit, which you were, but because you overtook us.”

Archer — who drives a convertible Mercedes E320 — thinks that the new-found assertiveness of women behind the wheel is linked to the increased pressure in their lives. “Women find themselves caught in a constant whirl of multitasking,” she says. “They’re rushing to drop the baby at the nursery before getting to work and delivering a presentation, talking on the mobile and slapping on their make-up at traffic lights. Of course we drive fast — I do because I’m perpetually late and stressed.”

Speeding penalties are regarded by some as not very serious — an occupational hazard on a par with parking tickets. Peter Marsh of the Social Issues Research Centre, author of a tome called Sex Differences in Driving and Insurance Risk, says the trend is alarming. “Over the past 10 years we’ve found that more women are involved in speeding offences and incidents of dangerous driving. Men are still involved in more speeding and dangerous driving than women, but the gap is narrowing.”

A Department for Transport study, Attitudes to Road Safety, found men were more knowledgeable about the speed limits that applied to different road types. In one question 53% of men answered correctly, compared with 39% of women. The implication is that men may be speeding wilfully, women by accident or neglect.

But nobody denies that women increasingly need to get to places in a hurry. “Women are catching up with men in all sorts of male preserves,” says Marsh. “Women are encouraged to be more ambitious and competitive in general and are becoming more masculine in their driving behaviour.”

Marsh also believes better cars cocoon their drivers, insulating them from the true speed at which they are travelling.

“The modern car no longer gives you that sense of impending mortality at high speeds. Women are now driving Volvos and huge 4x4s because they feel safe in them. They don’t rattle and shake at speed like the cars of old. The more protected they are, the less cautious these women will be. That’s nice for them, but very bad news for stray pedestrians and cyclists.”

But men keep their lead

Women may be driving faster but they still don’t speed as much as men, according to Diamond Insurance, which specialises in cover for women. Men are twice as likely to speed (11.6% of men in the year to September 2004 compared with 6.1% of women). Sian Lewis, the managing director of Diamond, says that male drivers tend to have more aggression and are involved in more serious accidents.

Last week the EU backed down on plans to stop insurance companies charging lower premiums for female drivers.

Ian Parker, the managing director of Privilege Insurance, welcomed this but warned that the insurance premium gap between sexes was narrowing. “Women have slightly fewer accidents but the difference is not as wide as some may think,” he says.