Fuel economy: the real story - The best and worst cars

In out What Car? economy test, the Ford Focus ST and Citroën C4 Picasso 1.6 HDi were the only two cars that managed to actually beat their official economy figures (by 3.0% for the Focus and 1.3% for the C4 Picasso).

In the Focus, that means you'd save £53 every 12,000.

Don't get too exited, though, because you'd still be squirting £1797 into the Ford's fuel tank every 12,000 miles (the average annual mileage).

The Ford S-Max 2.5 (fitted with the same engine as the Focus ST) was also impressive, and only 1.7% down on its official figure.

And the worst...
The Smart diesel was furthest from its official fuel economy (by a hefty 28.5%), but still managed a whopping 61.2mpg. That's the best figure of any of the cars we tested by some margin, and would mean the smallest fuel bills.

The next-worst car was the Toyota Prius, which was 20.3% worse than its official figures, but still second best overall at 56.3mpg. That's because real-world driving means its petrol engine cuts in far more often, which uses more fuel.