Hi I picked up my car yesterday after Bmw Indi Specialist locally fitted both new stats and blanking plates. I have driven the car since 100miles and only achieving 30 mpg on 70 mph cruise and 15mpg town runs. It was doing double before I handed car in. I had work done in the hop of improved mpg but it's almost halfed. I took car back today and the specialist fobbed me off and said the blanks must be causing it. But they stay on the computer it's all fine. I'm really concerned what they have done and not giving me a solution. Specialist used is - Cheshire BM 520d should not be achieving such low mpg. Temp is a constant 90c. Please help me anyone.