Real-world MPG: convertibles that beat 40mpg

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 look at the fuel economy of stylish drop-tops that won’t cost a fortune to fuel. These six convertibles all beat 40mpg in our test.

1. Mercedes E220 CDI Cabriolet – 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.

2. Vauxhall Cascada 2.0 CDTi 165 – official 54.3mpg: True MPG 47.4mpg

The Cascada is a proper four-seat drop-top, with space for two adults in the back as well as the front. It’s fairly large, which means it’s also fairly heavy, and none of the engines feels particularly potent. Still, this convertible is well equipped and has a comfortable, well-controlled ride. We’d recommend this 163bhp diesel, because it offers the best blend of performance, running costs and resale value.

3. 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 classy as the exterior.

4. Fiat 500C Abarth 1.4T – official 43.5mpg: True MPG 42.2mpg

The Fiat 500C’s retro charm will be enough for some buyers, but it’s also cheap to run, decent to drive and you can get a couple of adults in the back on shorter journeys. This turbocharged Abarth version is actually more efficient than the 0.9-litre Twinair (which managed 41.3mpg in our test), and offers strong performance along with a beefed-up bodykit. Like the DS3, you don’t get a full drop-top experience, but the 500C is extremely endearing nonetheless.

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 – unlike most of its siblings – it’s more affordable than its main rivals. The Coupe is the Mini that’s most fun to drive, but if you want the thrill of open-air motoring, the Roadster should be next on your test drive list. Its refinement isn’t on par with the best convertibles', but in Cooper S form it’s a fast and flexible car that’s well worth considering.

6. Audi TT Roadster 1.8 TFSI – official 43.5mpg: True MPG 40.7mpg

There are few cars in any segment that can rival the TT’s blend of style, high-quality cabin finish, reasonable running costs and driver appeal. Our favourite model is the 208bhp 2.0 TFSI, but this entry-level 1.8 won’t leave you feeling shortchanged – it still offers hot hatch pace. The next-gen TT Roadster is on the way, so discounts on this version are particularly strong. We’ve found savings of more than £3000 off list price.

We add new models to our True MPG database every week. 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.