Jaguar XF review - is the Jaguar's exec-saloon best in class? - MPG and Running Costs

WLTP regulations have seen the XF's engine lineup change over the past year or so and quoted economy figures have also taken a tumble – though it's important to realise that any such changes will also be suffered by competitors, so it's difficult to compare like-for-like until all manufacturers display WLTP numbers as a matter of course.

To illustrate the disparity, just take a look at how the numbers have changed for the entry-level diesel: What was previously capable (on paper) of 70.6mpg with a manual gearbox has now dropped to 55.4mpg. Almost certainly more realistic, but not quite as sparkling in the brochure. Likewise, CO2 has risen from a probably unlikely 104g/km to 129g/km.

With the automatic gearbox you don't lose a great deal, at 54.3mpg and 138g/km, while moving up to the 178bhp diesel with the auto 'box and all-wheel drive drops economy to 50.4mpg and raises CO2 to 148g/km.

The petrols aren't too bad on fuel – the 247bhp four-pot manages 44.1mpg – but for a mix of performance and economy the V6 diesel holds the trump cards, with 45.6mpg combined even after WLTP shenanigans and CO2 of 163g/km.