Overall, the Emissions Analytics data showed that cars with small engines had the biggest gap between official fuel economy and actual performance, and those with the biggest engines had the smallest gaps.
The Fiesta petrol returned just 38.7 against 65.7 but a BMW M140i returned 35 against 39.8.
The Golf 1.6 diesel and 308 1.6 diesel both claim 88.3 but only managed 53.
More worryingly, and getting back on track with the thread, new diesels are spewing out 4x the Nitrous Oxide they officially claim. I think over the next 10 years we shall see a sharp decline in new diesel vehicles. I would also caution against small petrol engines as these do not have the durability of larger ones and in reality offer little improvement in fuel efficiency. In my view 1.4 is small enough.