Real-world MPG: best convertibles that beat 40mpg

  •  Four great convertibles beat 40mpg in our test
  •  Brilliant drop-tops that are also fuel efficient 
  •  Results indicate real-world fuel economy 
Want a fuel-efficient convertible? BMW's 420d Convertible is one we'd recommend
Want a fuel-efficient convertible? BMW's 420d Convertible is one we'd recommend

What Car?’s technicians drive new cars every week to capture our True MPG fuel economy data. Unlike official Government figures generated by a laboratory test, the numbers we publish are gained from real-world conditions.

This week we’re looking at the most economical convertibles we’ve tested so far, with a What Car? rating of four or five stars out of five. If you want an impressive drop-top that should do more than 40mpg in real-world driving, these four models should be on your shortlist.

1. BMW 4 Series Convertible 420d SE – officially 55.4mpg, True MPG 49.4mpg

The 4 Series Convertible delivers pretty much all that could be asked of it. It's refined enough with the roof up to be an everyday tool, yet stylish and accomplished enough with it down to be a relaxed, sophisticated cruiser. Just be aware that this diesel engine is gruff at low speeds, and that you need to add the adaptive M Sport suspension to make this drop-top ride and handle as well as it should.

2. Mercedes E-Class Cabriolet E220 CDI – officially 58.9mpg, True MPG 47.6mpg

The E-Class Cabriolet’s recent face-lift means that our previous favourite model (the E350 SE) is no longer available. Fortunately, the four-cylinder diesels are now much more refined, and we think this entry-level E220 CDI now makes the most sense. We still recommend SE trim to get the most comfortable ride, and the seven-speed automatic gearbox to get the smoothest gearshifts. In this combination, it’s a classy, commendable cruiser.

3. Citroen DS3 Cabriolet 1.6 VTi – officially 49.6mpg, True MPG 45.2mpg

Small convertibles don’t come much more stylish than the DS3 Cabriolet, although the retractable fabric roof is more of a big sunroof than a full drop-top. Still, it can be put back in place at up to 74mph. The DS3 is good to drive, with this 1.6 VTi engine being the best match for leisurely motoring. You get plenty of kit as standard – especially in DStyle trim – and the cabin is just as funky as the exterior.

4. Mini Roadster 1.6 Cooper S – officially 47.1mpg, True MPG 40.8mpg

The Roadster is one of our favourite Mini models, largely because it’s more affordable than its main rivals. If you want the thrill of open-air motoring in a car that’s also fun to drive, this Mini should be near the top of your test drive list. Its refinement isn’t on a par with that of the best convertibles, but in Cooper S form it’s a fast and flexible car that’s well worth considering.

Want to find out what you can really expect to achieve on UK roads? Visit to see the full range of cars we’ve tested. We add new models to our True MPG database every week.


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