My c5 2.0 hdi exclusive with an auto box gives me 42mpg on high speed motorway runs, this is well below the manufacturers figures but that is because the manufacturer doesn't use real world driving. Thier figures are achieved usinng a set criteria in a laboratory and are intended to give a comaprision from new car to new car. Nowhere do they actually claim you will get those figures. You only need to look at the Mitsubishi outlander 4x4 which is claiming 148 to the gallon, but it is a hybrid and they do not tell you what it costs to plug it in and charge it. Yes you do plug it in unlike the toyotas.