@Greenie222; welcome to the forum.
You could try manually calculating your fuel consumption over a period of a few months and a number of tank fill ups. That’ll help you determine whether or not the car’s fuel computer’s mpg calculation is accurate or not and if it isn’t, the manually calculated figure should be pretty accurate over a longer period of time. If much of your driving is 10 mile journeys, then bear in mind that your car’s engine won’t be fully warmed up for maybe up to half of that journey distance, and mpg will always suffer on a cold engine. However, I’d say that what you’re seeing mpg-wise is probably within the limits of what you’d expect.
Below are VW’s ‘official’ fuel consumption figures for the mk6 GTI from the December 2010 brochure. Bear in mind that the official figures tend to be somewhat optimistic and are rarely - if ever - achieved in normal day to day driving. Link to the brochure;
https://www.volkswagen.co.uk/assets/common/pdf/brochures/golf-vi-brochure.pdf
It might be worth checking your tyre pressures to ensure they’re inflated to the correct pressure; under-inflated tyres can have an adverse impact on mpg. Also, if you’re carrying any unnecessary ‘baggage’ in your car that’s adding weight, then it’d be worth removing it.
I don’t have a mk6 Golf GTI but by way of comparison, in my 2020 Polo GTI+ (EA888 gen 3b 2.0 litre 197bhp engine) with DSG transmission I usually see low to mid 30’s mpg when driving around town. On longer ‘A’ road journeys (which is most of my driving) and just going with the flow of the traffic, which is the norm at the times of day I’m usually driving because of the traffic conditions, my mpg is mid 40’s on those journeys. I rarely do any motorway driving these days.
Overall, my long term average fuel consumption is around 41 - 42 mpg.
