True MPG: the most and least efficient cars revealed

What Car?'s laboratory tests use a real-world driving route to show what fuel economy you can really expect. So, what are the best and worst performing cars?.....

What Car?’s True MPG real-world fuel economy figures show what sort of efficiency you can really expect from a car.Image 1 of 20

Tests are conducted in a laboratory under tightly controlled conditions to ensure repeatability within 1%, but they are based on a real-world route that takes in town, rural and motorway driving.

The results reflect what's achievable if you’re driving gently and sticking to speed limits, but aren’t resorting to any unrealistically slow acceleration or special 'hypermiling' techniques. As a result, True MPG is not only fully reflective of real-world performance, but much more realistic than the official government fuel economy figures that car manufacturers have to quote.

Below we count down the top 10 performers – and reveal the 10 cars that used the most fuel. The 10 most fuel-efficient cars tested: