Article in The Guardian this morning (although not online yet) that Which magazine has tested cars for real-life MPG. Average discrepancy with official figure is 13% worse but PHEV wins the prize for biggest difference, 136%, with an implied £459 in "unexpected fuel costs per annum". Which got 67.3mpg in their own tests compared to the 148mpg official figure. They admit that this is still a good result for a large car.