The alcohol interlock programme should be made mandatory, the AA says.
Interlocks work by making drivers undergo a breath test before a car's ignition can be started.
MPs at a select committee are considering a law change that would lower the drink driving limit from 80mg of alcohol per 100ml of blood to 50mg.
The interlocks were introduced in September 2012 but have so far been used only 158 times, AA senior policy adviser Benjamin Young told the committee.
He said defendants were arguing before courts for their licences to be suspended rather than interlocks fitted.
