SIPP codes are a widely used car-rental vehicle classification standard maintained by ACRISS. They use a four-letter code to describe a vehicle’s category, body type, transmission or drive, and fuel or air conditioning, which helps customers compare different vehicle classes. The system is voluntary but widely adopted across the industry.
The codes are commonly called SIPP codes, a legacy term often explained as meaning Standard Interline Passenger Procedure, because this was the name used when the system was first introduced in earlier travel-industry standards. As ACRISS now maintains the classification matrix, the codes are also known as ACRISS codes. Both terms refer to the same system. SIPP code remains common due to long-standing use, while ACRISS code reflects the organisation currently responsible for maintaining the standard.
