Real-world MPG: Vauxhall diesels
The Vauxhall Zafira Tourer 2.0 Biturbo achieved 45.4mpg in our tests, which is only 5mpg shy of its official figure. It's not the most efficient 2.0-litre diesel we've tested, but it's a respectable result given its power output of 192bhp. In comparison, the 197bhp Ford S-Max 2.0 managed 39.6mpg in an earlier test.
The Vauxhall Cascada 2.0 also came close to its Government figure, with fuel economy of 47.4mpg in our tests, compared with a its official economy of 54.3mpg.
Our tests found that the Mini Paceman JCW had the smallest gap between True MPG and Government figures during this period – the 33.7mpg recorded by the True MPG team is only 4.5mpg short of the official 38.2mpg. However, the BMW M135i is only slightly more expensive than the Mini, despite having another 101bhp, and returned 33.9mpg in previous tests.
The biggest gap between official figures and our data was for the 1.4-litre Alfa Romeo Giulietta in more powerful 168bhp guise. Its Government economy is 48.7mpg, but our True MPG tests indicate real-world efficiency will be closer to 31.9mpg.
Visit whatcar.com/truempg to see the full range of cars we've tested, and find out what you really can expect to achieve on UK roads.
By Ed Callow