I have a 55 plate Croma Eleganza JTD150 and recently filled it with BP Ultimate fuel. I have since found that I get an extra 5mpg per gallon; increased from 42 to 47 mpg over standard fuel. OK the fuel costs more but the % increase in cost is far outweighed by the increase in economy. No I don't work for BP but would be interested to hear if anyone knows of similar experiences or any reason not to use this type of fuel (I had always considered it for high performance cars like Impreza etc).