mpg question

[billza1967]

hi everyone again what would cause a passat 130 tdi to eat the fuel car starts and runs great but its eating the fuel the computer says 42 mpg but im lucky if i get 30 im taxiing the car but its costing a lot for fuel i drive the car normal infact im driving like a nun cos im scared to put the foot down its had another new head fitted cos vw cocked up the first time new coolant sensor fuel sensor map sensor ive recently changed the egr valve for a second hand one off ebay could that cause it any help would be appreciated also when im driving at night if i do pull a way and theres a car behind theres clouds of smoke i can see it in the headlights of any car behind me cheers bill