The Automotive Directory Featured Sites Used Cars Used car listings and dealerships across the country, as well as informative articles for the used car buyer and seller. Listings Guardian Interlock Systems - connects a breath analyzer to a vehicle's electrical system. Once installed, the driver must pass a breath test before starting the vehicle to prove sobriety. Interlock Systems of Iowa - breath alcohol testing equipment that acts as an ignition interlock device. Intoxalock - a breath alcohol ignition interlock device (BAIID) that prevents an intoxicated person from driving. Sens-O-Lock Distribution of New England, Ltd. - makers of ignition interlock devices for all types of vehicles. Smart Start - provides vehicle ignition interlock services for DWI offenders that require breathalyzer alcohol testing prior to operating a vehicle.