Real-world MPG: most economical convertibles

  •  Six great convertibles beat 40mpg in our test
  •  Brilliant drop-tops that are also fuel efficient 
  •  Results indicate real-world fuel economy 


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 at least three stars out of five. If you want an impressive drop-top that should do more than 40mpg in real-world driving, these six models should be on your shortlist.

1. BMW 4 Series Convertible 420d SE – official 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 – official 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. Vauxhall Cascada 2.0 Elite CDTi – official 54.3mpg: True MPG 47.4mpg

For a mid-size convertible, the Cascada has a particularly roomy interior with genuine space for four adults. It’s also a refined car on the road, with little flex through the body and the standard suspension does a good job of filtering out pockmarked roads. The heavy body does make it feel inert at times and compared to rivals it is expensive.

4. Citroen DS3 Cabriolet 1.6 VTi – official 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.

5. Mini Roadster 1.6 Cooper S – official 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 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.

6. Audi TT 1.8 TFSi S-Line Roadster – official 43.5mpg: True MPG 40.7mpg

The Audi TT Roadster is an effortlessly stylish car, which has talents beyond just its striking looks. For the MkII version Audi breathed some magic into the chassis, so that the ride and handling are a match for its kerb appeal, and the interior has that typical Audi hewn-from-granite feel. On the downside, the convertible is a strict two-seater and with the hood up, rearward visibility isn’t great. The model is on the cusp of being replaced, so haggle hard on the out-going model, as there should be some great deals.

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


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