hi i have a astra h 1.9 cdti 150bhp. im currently only getting around 34 -36 mpg at best in non sport mode. my mate has a 2003 1.9 tdi golf and on the same run is easily getting 40mpg to mid 40s. iv managed to get high 38mpg when in sport mode on the same road to work. tried injector cleaner with no luck. even did a long run to alton towers the other week and it didnt move above 36mpg. is this normal or should i be getting more?