True MPG: most efficient diesel cars

What Car?'s True MPG tests show what fuel economy you can really expect from a car. Here, we reveal the best-performing diesel-powered cars we've ever tested...

Vauxhall Insignia Grand Sport
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What Car? team
25 Mar 2019 16:00

7. Vauxhall Insignia Grand Sport 1.6

True MPG 51.8mpg

The Insignia Grand Sport is a popular choice among company car drivers, and it's easy to see why: it's well equipped, entry-level versions won't cost you very much to buy and it's competitive on benefit-in-kind payments. This 134bhp 1.6-litre diesel engine is the sweet spot in the range.

New Mitsubishi Eclipse Cross vs Nissan Qashqai vs Skoda Karoq

True MPG 51.9mpg

The Qashqai is consistently ranked among the best-selling cars in the UK, and fortunately this diesel-engined version is also among the most frugal, returning almost 52mpg on our tests. In addition, the Qashqai is one of the most comfortable family SUVs on sale, as well as being reasonably spacious.

Read our full Nissan Qashqai review, or see our latest Qashqai deals

5. BMW 4 Series 420d 

BMW 4 Series Coupe

True MPG 52mpg

The second coupé to feature on this list is the elegant 4 Series, which is a chief rival to the Audi A5 we mentioned on the previous page. Although there are more powerful engine options available, this 2.0-litre 420d model is our recommended choice for its speed and flexibility. The 4 Series is well equipped and fun to drive, plus there's space for four inside. It's also available as a convertible if you're looking for roof-down thrills.