I think you have made a mistake with the dates. The original (Mk1) Rabbit was available in 1974,
You're right about the basic Golf (Rabbit ) being available in 74, but the Golf GTI didn't actually come to market in Europe until 1976...
What I love about the Golf GTI story is that the reason for its existance was that a group of car enthusiasts working at VW (engineers, designers, ect) loved the basic chassis so much and thought it had so much more potential that they spent their off time looking for ways to make it a inexpensive sports car....it was an unofficial project even at VW AG for quite a long time until they could convince the execs to make it a offering to the public. It really was about love of the car in this case and not just profit. I doubt you can find something similar in the modern day industry.