They aint good on fuel, both 8 and 16v versions drink due to where the engine power bands are and related outputs.
A VR6 can be just as economical to drive as it does not need as much full throttle to make it just as fun.
Quarter of a tank goes quicker than it should, this has been the case on all of my Mk3's
If you want performance and economy then you need a newer generation car or a (spits) fast Diesel.