Abstract: A motor vehicle antitheft alarm provides complex sounds, is disabled in normal use of the vehicle, and is resistant to "hotwiring" of the ignition notwithstanding. Unauthorized motion of the vehicle causes a disturbance sensor to activate the alarm circuit. Qualitatively different alarm sounds are provided in response to repeated disturbances as compared with isolated ones. When the ignition is turned on in normal use, a first voltage condition is provided to disable the alarm apparatus. After the ignition is turned off a short time of disabling is provided to permit the user to leave the vehicle before the alarm can be activated. An anti-hotwiring turn-on circuit associated with the ignition switch provides a second voltage condition, or allows same, blocking the first voltage condition from occurring during hotwiring. A voltage-sensitive circuit sets off the alarm when the second voltage condition occurs, deterring hotwiring.