cruisiing it should be achievable.
When I tried, i could get the long term average up to 37mpg, but any 'press on' driving, excessive town driving or 80mph+ and it soon drops to 30ish. As a comparison, I owned a 2.0 Bora (same as golf gti engine) a 1.6 8v Bora and both were less economical than the 1.8T in similar driving.