In association with Nissan LEAF
True MPG: most efficient coupes, convertibles and sports cars 2020
What Car?'s True MPG tests show what fuel economy you can really expect from a car. Here, we reveal the best and worst-performing coupés, convertibles and sports cars we've tested...
The miles per gallon (MPG) figures published in sales brochures can tempt you into buying a particular car, but those results are often misleading. Fortunately, What Car?'s True MPG tests reveal what sort of fuel economy you can expect in the real world.
To ensure accuracy and repeatability, we use strictly controlled laboratory conditions, but the tests 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.
Here we reveal the 10 most efficient coupés, convertibles and sports cars we've tested so far – plus the one that used the most fuel.
The 10 most fuel efficient coupés, convertibles and sports cars cars:
10. BMW M2
True MPG 31.4mpg
The M2 is effectively a steroid-enhanced version of the BMW 2 Series. Under its bonnet lies a turbocharged 3.0-litre engine that pumps out 365bhp – enough for a 0-62mph time of 4.4sec with the standard six-speed manual gearbox. Yet you can still get 31.4mpg out of the car when you drive it more gently.
Read our full BMW M2 review >>
9. Porsche 718 Cayman
True MPG 34.4mpg
Both this entry-level version of the Cayman and the more powerful Cayman S swapped their flat six engines for turbocharged four-cylinder units back in 2016 in order to reduce fuel consumption and emissions. The downside is that they no longer sound as special as they did.
Read our full Porsche 718 Cayman review >>
8. BMW 4 Series 43oi Convertible
Save money on a new BMW 4 Series Convertible with What Car? >>
True MPG 34.9mpg
Fractionally more efficient than the Cayman is the BMW 430i Convertible, despite it being a four-seater with a folding metal roof, so considerably heavier.
Read our full BMW 4 Series Convertible review >>
7. Audi TT Roadster 1.8 TFSI
True MPG 39.8mpg
We've always rated the TT Roadster highly, with this version's near-40mpg average fuel economy joining a list of attributes that also includes sharp handling and a gorgeous, high-tech interior.
Read our full Audi TT Roadster review >>
6. Audi TT Coupé 1.8 TFSI
True MPG 40.4mpg
As good as the TT Roadster is, it's the hard-top version that we'd choose; indeed, no car has won more What Car? awards than the TT Coupé. It's even better than the Roadster to drive and that bit more practical and efficient.
Read our full Audi TT Coupé review >>
5. Mini Convertible Cooper
True MPG 43.4mpg
There are more practical drop-tops than the Mini Convertible, because its rear seats are distinctly cramped. However, with strong resale values and a True MPG figure of 43.4mpg, it still makes plenty of sense.
Read our full Mini Convertible review >>
4. Fiat 124 Spider 1.4 140
True MPG 44.2mpg
The 44.2mpg that the Fiat 124 Spider managed in our True MPG test isn't just impressive for a convertible sports car, but also slightly more than its official average. You also get peppy performance and a supple ride, but will have to scour the classifieds if you want a 124 Spider, because it has been discontinued due to slow sales.
Read our full Fiat 124 Spider review >>
3. Mazda MX-5 2.0
True MPG 45.1mpg
The MX-5 is closely related to the 124 Spider and actually more fun to drive, but instead of a turbocharged 1.4-litre engine, it uses a naturally aspirated 2.0-litre unit. In official tests, that makes it slightly less efficient. However, we found it actually averages 3.7mpg more than the Fiat.
Read our full Mazda MX-5 review >>
2. Audi A5 Coupé 2.0 TDI 190
True MPG 50.8mpg
The A5 Coupé is closely related to the A4 saloon that won our overall Car of the Year Award when it first came out, meaning it's comfortable, beautifully built and as quiet as it is efficient. It's even quite practical by coupé standards.
Read our full Audi TT Coupé review >>
1. BMW 420d Coupé
True MPG 52.0mpg
In addition to being more fuel efficient than any other coupé we've tested to date in its diesel form, the 4 Series is fun to drive, well equipped and spacious enough for four. True, it's due to be replaced later this year, but if you're not bothered by that, the good news is it makes big discounts easier to come by.
Read our full BMW 4 Series Coupé review >>
And the least fuel efficient coupé, convertible or sports car...
Alfa Romeo Giulia Quadrifoglio
Save money on a new Alfa Romeo Giulia Quadrifoglio with What Car? >>
True MPG 23.5mpg
With a 503bhp twin-turbocharged petrol V6 under its bonnet, the Giulia Quadrifoglio is designed for performance rather than efficiency, and that's reflected in its poor True MPG result. However, it's our reigning Performance Car of the Year, which tells you just how good it is at the things it specialises in.
Read our full Alfa Romeo Giulia Quadrifoglio review >>
For all the latest reviews, advice and new car deals, sign up to the What Car? newsletter here
Read more: the most efficient and least efficient cars >>
Find a car's True MPG >>
Best coupés 2023
Tempted by the idea of a stylish coupé car? Then check out our comprehensive rundown of the top 10 best models on the market – and find out which one we'd avoid
Audi TTS long-term test
The Audi TTS is a stylish coupé with fun at its core, but does it still have a place in a world dominated by high-riding SUVs? Our deputy editor is living with one to find out