Preventing Auto Recycling Theft Act or the PART Act This bill establishes requirements for motor vehicles related to catalytic converters and other motor vehicle parts that contain precious metals. The National Highway Traffic Safety Administration must revise the motor vehicle theft prevention standard for new motor vehicles to include catalytic converters among the parts that require an inscribed or affixed identifying number. Additionally, the Department of Transportation must establish a grant program through which law enforcement agencies and other entities can stamp vehicle identification numbers onto catalytic converters of existing vehicles. The bill establishes retention requirements for the purchase of motor vehicle parts that contain precious metals. It also sets forth criminal penalties for the theft of catalytic converters or any precious metals removed from a vehicle.