Young Irish motorists are being offered 30% off their high insurance premiums if they accept an 11pm to 6am driving curfew.

The scheme has been introduced by the Hibernian Group, the largest insurer in the Irish Republic, at a time when the cost of cover for drivers under 25 is higher, in some cases, than the cost of their cars.

Insurers say this reflects the high accident rate involving young motorists, but one 22-year-old is taking action against his insurer under Irish equality legislation, alleging discrimination on grounds of age.

Despite a clean driving record, he is being asked to pay a premium of more than IR£4,000 (£3,125).

Under the new scheme, which is being operated in association with the UK-based Institute of Advanced Motorists, drivers who successfully complete a free one-day intensive training course, involving driving hazards and behaviour, will earn a 20% cut in their premiums. They will qualify for an additional reduction of 10% by staying off the roads from 11pm to 6am, described by Hibernian's managing director, Gary Owens, as “the killing hours”.

Those who break the curfew and are involved in accidents will be expelled from the scheme and face full premiums on renewal.

One thousand drivers under 25 will be trained between October and December, with a further 4,000 from January. Initially, the scheme will focus on Hibernian clients of three years' standing, their children or named drivers on a company policy.

According to the company, the savings can be significant. A male driver aged 23 and living in Dublin, who took the full 30% offer – the training course and curfew – would have his current premium of IR£2,673 (£2,100) cut to IR£1,871 (£1,467). A 21 year-old female driver, also in Dublin, would pay IR£1,311 (£1,028) instead of IR£1,873 (£1,468).

The scheme has been welcomed by Irish Environment Minister Noel Dempsey and the National Safety Council, who said it would help reduce the country's high road toll.