Real MPG: most economical luxury cars

The official MPG figures published in car sales brochures can tempt you into buying a certain model, but those results can be misleading, so you may not be able to match the figures when you take the car home. To show you the sort of fuel economy you can expect in real-world use, we conduct our own Real MPG tests.

We're counting down the top 10 most economical luxury cars, starting with the most economical: the 2016-2024 Mercedes E-Class. The best luxury cars are desirable, and sought after for their sumptuous interiors, high levels of comfort and supreme refinement. Buyers' expectations are high, then, and despite the obvious opulence, decent fuel economy is still an important factor.

So, here are the models which cost the least – and the most – to run.

How we test for a car's Real MPG

Our Real MPG tests are carried out on a rolling road under laboratory conditions. That means variables such as weather and traffic can’t affect our results, ensuring that they’re comparable. The routes the cars take are based on a realistic mix of roads.

Every car we test is weighed and has its tyre pressures checked, then we hook up an exhaust connection to measure the car's emissions. The car's climate control is set to 21 degC or, if it has manual air conditioning, the temperature is set to its midway point, and the fan speed to its lowest setting. We turn off the headlights and don't use other electrical equipment, such as heated seats or the stereo.

In the test, we sample each car's tailpipe emissions every second. The Real MPG scores you see in this story are calculated from an average of those results.

Read more: How we test a car’s Real MPG