Don sez: "As to the cost of the initial [BTI} equipment, it shouldn't add more than £30 - £40 to the cost of a car. Pretty insignificant I'd have thought, and as a driver sharing the road with drinkers, wouldn't you think that an extra £40 on the price of your car is a small price to pay for being protected from others who drink and drive."

Hmmm? Having a breath alcohol immobilizer as standard equipment on my new car isn't going to protect me from others who drink and drive older-model cars without BTI's. That's why I was asking whether you envision a law requiring BTI's to be retro-fitted onto older cars. If there were no such law in your scenario of new-cars-with-BTI's, then I think teetotalers with new cars would object strenuously to being monitored while drunk drivers with older cars are not!

Again, I have to ask: would a BTI immobilize a car when the driver had a trace amount of alcohol on his breath -- if he had just ingested a bit of cough syrup or had just gargled with Listerine? Also, would the unit detect a strong scent of alcohol being exhaled by a very drunken passenger that a designated driver was transporting home, and would the unit then prevent the driver's car from being started? Would a car with a BTI, once started, keep running if the sober driver popped into a bar and left the engine running and got back into the car drunk?