Regular readers of the Jaguar XF updates will know that the car has performed significantly worse than expected for fuel consumption.
Typical fuel consumption according to the trip computer was around the 40-42mpg mark, which is more than 20% adrift of the official combined fuel consumption figure of 52.3mpg.
What made matters slightly worse is the accuracy of the trip computer. While it was showing higher than 40mpg, actual fuel consumption calculated from brim to brim suggested 37-38mpg was being achieved.
I decided to take drastic action to see if the official 52.3mpg could be achieved.
However, we are well aware that the official combined fuel consumption figure is derived in a test far removed from day-to-day driving, and the combined figure itself is merely a calculation – an average of the urban and extra urban figures.
But other cars we have tried seem to fare much better in relation to the official figures. For example, the Mercedes-Benz E220 CDI automatic regularly achieves more than 50mpg, closer to its official 57.6mpg.
It’s also frustrating knowing that the XF is using the same eight-speed automatic transmission produced by ZF and supplied to BMW for the latest generation of cars. Obviously BMW sets the class benchmark in many of its sectors for fuel consumption.
It would be disappointing for any driver claiming a mileage rate, and potentially frustrating when funding their private mileage, if they’ve chosen the Jaguar because of the new four-cylinder engine only to find its fuel economy is below expectations.
I drove on a whole tank of diesel with the gearbox in winter mode. To improve safety and performance in icy conditions the gearbox usually starts in second gear to avoid wheelspin when pulling away, and changes up through the gears at lower rpm.
One of the side effects of this mode is lower fuel consumption, and on a long run to Gatwick airport the trip computer showed as much as 54mpg, although for the whole trip settled on 50mpg.
Success, but I can’t help feeling there would have been an even better result in another car.
We will continue to experiment during the Jaguar’s last month with us and hope for more improvements.