Anyone use Android Torque on here? - Couple of questions

[pb25]

Bought myself a bluetooth OBD and torque.....

On the car profile I have added 12.5 Imperial gallons as the fuel tank size (55 litres / 4.4) but the MPG is utter pants....most of the time it says I'm getting 9 miles to the gallon in a 2.0 TD!!! Am I missing something here?

Also the boost gauge is all over the shop....sometimes it will peak at 15.5 others its nearer 30. I have tried -14.7, 0 and 14.7 in the car profile for the adjustment for atmospheric pressure. No one reading seems to give a constant set of reading from trip to trip. Am I missing something here aswell?

Any help much appreciated