The internal designation (Typ number) for the Volkswagen Golf Mk4 is Typ 1J.
Volkswagen introduced the fourth-generation Golf in 1997 for the 1998 model year. Its factory designation, also written as VW Type 1J, identifies the Mk4 hatchback and its closely related derivatives. The car used Volkswagen Group’s A4, or PQ34, platform, shared with models such as the first-generation Audi A3 and the New Beetle.
The Mk4 represented a deliberate move upmarket from the Mk3, with a more substantial interior, tighter panel fit and greater equipment. Production began in Europe in 1997 and continued in some developing markets long after the Mk5 replaced it in Europe.
A common mix-up is Typ 1K, which belongs to the Golf Mk5. Typ 5G identifies the Mk7, while Typ 17 belongs to the original Golf Mk1. Those numbers are internal model codes, not engine sizes, platform names or trim levels.