The first version debuted in 1974 and was originally based on the engineering concept of the Volkswagen Golf Mk1, and is applicable to either front- or four-wheel drive vehicles, using only front-mounted transverse engines.
Volkswagen Group introduced a new alphanumeric nomenclature for vehicle platforms for the fourth generation.
A1 platform cars (Typ numbers in brackets): The A2 platform debuted in 1983 on the Mk2 Golf, and lasted until 1998, when the original SEAT Toledo (the first Volkswagen-developed SEAT following the Spanish company's takeover by Volkswagen) was replaced.
The A4 platform (PQ34 under the revised scheme) debuted on the Audi A3 in 1996 and went on to be used for many different models over the next two decades.
For the first time, a fully independent suspension was used in the rear of all A platform vehicles.