Hello,my v230 seems to have more faults than any previous mercs I have owned.It was converted to lpg 7 months ago and runs fine.however it is only averaging 17 to the gallon on petrol.Luckily on gas it is the equivalent of about 35 mpg.The main problem now is when I accelerate whilst on LPG ,exhaust fumes are entering via the heater ducts.Any ideas?Thanks a lot Graham.Ps what sort of mpg should I expect ?