Media playback is unsupported on your device Media caption Twins Nick and Emma Lane differ greatly in the amount of car insurance they each pay

Young women could face big increases in the cost of car insurance, if insurers are told that they have to stop quoting different prices for men and women.

The European Court of Justice will decide whether it is a form of sex discrimination which should be banned.

If so, some women drivers in the UK could eventually face 50% rises in the cost of insuring their cars.

The ruling could affect the cost of pension annuities, life assurance and health cover as well.

The gulf between men's and women's motor cover is particularly wide for drivers who have recently passed their tests.

Nick and Emma Lane, a brother and sister from Bishop's Stortford, feel the difference more acutely than most.

'Ridiculous'

Nick and Emma are twins. They are 18 years old, so they suffer from the highest insurance rates.

The facts show young male drivers are most at risk of accidents on the road Nick Starling, ABI

More than that, they each had three attempts at the driving test before passing. And they succeeded within weeks of each other.

They are as similar as drivers can be, apart from the difference in sex.

Yet when they fed their details into an online price comparison site, Nick's motor insurance quote was twice as high.

"I don't like it all," Nick says. "I think it's ridiculous that I have to pay double the amount she does when we're not actually that far apart in terms of driving ability."

Lower premium

The Association of British Insurers (ABI) argues that people get a deal which accurately reflects their situation.

Image caption Insurance broker Mike Williams thinks it is unlikely that men's premiums will come down

"The facts show young male drivers are most at risk of accidents on the road, so young women currently pay a lower premium for their car insurance," explains the ABI's Nick Starling.

The quotes that Emma and Nick received were for a 1.2 litre Vauxhall Corsa from 2003. They reflect the 58% increase in rates suffered by the 17-22 age group over the past year.

But while Emma's best quote was an uncomfortable £1,700, Nick's was an eye-watering £3,400.

"It does seem a bit unfair," says Emma. "But it's all right for me because I have to pay less."

Of course, if the ruling goes against her then, eventually, she would have to pay a great deal more.

Wishful thinking

The ABI suggests that young women could face an average increase of 25%, rising to 50% for the least experienced.

Research published by the insurers at the end of last year estimated that men under 25 could expect a 10% fall in premiums on average.

That is wishful thinking, according to many in the insurance industry.

"It's entirely certain that women's premiums will go up. I don't think there's any chance whatsoever that men's premiums will come down," says a leading insurance broker, Mike Williams.

"And the reason for that is that men have more accidents and when they have accidents they're more expensive."

And Nick Lane has this confession to make: "I did nearly kill a cat in one of the driving tests I failed. But I'm really not that bad a driver."