The mpg figures published in sales brochures can tempt you into buying a particular car, but those results can be misleading. Fortunately, What Car?'s True MPG tests reveal what sort of fuel economy you can expect in the real world.
To ensure accuracy and repeatability, our tests are conducted under strictly controlled laboratory conditions but based on a real route that takes in urban, A-road and motorway driving.
Best real MPG executive and luxury cars
Official fuel economy: 50.4mpg; True MPG: 35.1mpg; Shortfall: 30.3%
The S-Class sets the pace for luxury saloon technology. More often than not, it’s the first model to feature the latest advance – on the latest version you can get suspension that uses windscreen-mounted cameras to monitor the road ahead and prepare the system for potholes. Its fuel-saving tech is up there with the best, too, hence the real-world 35.1mpg we achieved in it.
Watch our video review of the Mercedes-Benz S-Class
7. Jaguar XF 3.0 V6 diesel
Official fuel economy: 51.4mpg; True MPG: 38.1mpg; Shortfall: 25.8%
The German triumvirate of Audi, BMW, and Mercedes-Benz, have dominated the large exec sector for many years with their respective A6, 5 Series, and E-class, models, but with the XF, Jaguar tackles them head on. Its six-cylinder diesel-engined model is our favourite because it offers seriously strong performance and reasonable fuel economy.
Watch our video review of the Jaguar XF
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