Idle Reduction and Natural Gas Vehicle (NGV) Weight Exemption
Any motor vehicle equipped with an auxiliary power unit (APU) or other idle reduction technology may exceed the gross, axle, tandem, or bridge formula weight limits by up to 400 pounds (lbs.). To be eligible for the weight exemption, the vehicle operator must be able to provide written proof or certification of the weight of the APU and demonstrate or certify that the idle reduction technology is fully functional at all times. Any NGV may exceed the limits by up to 2,000 lbs.
(Reference Code of Alabama 32-9-20)