I might be wrong here... but at the moment the Golf is the third car in to range of VW's
(Smallest to largest the golf is third)
Back in 1976 the Golf was the smallest (i think)
if VW keep it all like this and dont add any more cars in ... eg
Lupo
Cricket (made up new car)
Polo
Golf
Then the Golf will always be the third smallest and it wont alter in size much, as long as the others dont. Vw dont want two cars almost identical in size.