Lots of factors will influence mpg - e.g.
- whether or not engine has an opportunity to get up to optimum operating temperature
- volume of traffic on the road
- if your journeys to work are short on a cold engine, then your car will be running at its least efficient and mpg will be poor, especially if combined with peak traffic times and lots of stop start work
- whether car is fully laden or driver only
- tyre pressures; if under inflated, mpg will suffer
- with the lower bhp 1.0 engine, there may be a tendency to use a bit more of a lead foot for acceleration and to maintain momentum, which won’t be good for mpg
There will be other factors too.
Are you calculating your mpg figures manually or relying on the figures calculated by the car’s computer? If the latter, then I’ve found in my current and previous four VW’s these can be out by up to 5 - 7%.
In my Polo GTI+ (2.0 litre with 6 speed DSG) my long term average is around 41-42 mpg. Shorter in-town trips I usually get 30-33 mpg and on longer journeys it’s usually mid to upper 40’s.