Hello, I hope the following is of assistance.
Given the mileage you did and the amount of fuel the car is doing over 37 MPG. Given that at the moment it's winter and the load from electrical items on the alternator will increase fuel consumption. If the car has A.C this alone when in use can increase fuel consumption by 10%, also remember the A.C will switch on automatically when the heater is set to demist.You may find in summer the car exceeds 40 MPG quite easily.
The type of driving can also have a huge impact on fuel consumption, town driving uses significantly more fuel than driving at 60 MPH on a dual carriageway.
The figures quoted by manufacturers for fuel economy will never be achieved on the road, the figures are for a set laboratory test and are used so consumers can compare the fuel economy on different models.
I hope this clarifies things for you but if I can assist further let me know and I'll reply as soon as I'm able to.