The State Government has introduced legislation to install breath-testing immobilisers in the cars of some of the State's worst repeat drink driving offenders. Road Safety Minister Liza Harvey said after 10 years of talk about alcohol interlocks, the Liberal National Government was acting to target recidivist drink drivers.

The devices would be fitted to the vehicles of drivers once they have already served their drink driving penalty or successfully apply for an extraordinary drivers licence and would be in place for a minimum of six months.

Their vehicles would only start if the driver blows under 0.02 and would come at a cost of around $1,600 to the driver.

"Once a driver blows under 0.02 the vehicle will start, however it may require periodical re-tests during the journey,” Mrs Harvey said.

“The scheme will capture first time offenders convicted of driving under the influence of alcohol and repeat drink drivers who have been convicted of two or more drink driving offences within a five-year period.”

Alcohol is a factor in about one quarter of fatal crashes and one in 10 serious injury crashes on Western Australian roads.

The financial cost of those injuries is estimated to be about $460million a year.