I average 30mpg round town and I like to drive her "Enthusiastically"
Top end the GTi is quicker and I think the 0-60 is too... But you have t allow that a 20 year old bog standard car is not going to be as fast as when it was new... But they also say that it take a Golf GTi 90K to get run in...
If you want more its easy to upgrade...
You also have to weigh up Insurance, a Mk2 can be done on a classic policy with Ltd mileage...
Parts are cheap and on the whole easy to get... and you can work on it yourself without having to be a mechanic... good set of spanners, socket set & some screwdrivers...
Needless too say a computer to get on here to find out what to do with the tools...
Haynes manual helps too...