Mercedes C-Class Cabriolet vs BMW 4 Series Convertible comparison

On paper, the latest Mercedes C-Class Cabriolet looks like the perfect everyday convertible. This graceful four-seater shares much in common with the excellent C-Class saloon, making daily use completely stress-free.

It does, however, have some serious competition in the shape of the BMW 4 Series Convertible. Its closest rival makes use of a metal folding roof instead of the fabric design used by the Mercedes. Read on for help deciding which deserves a place outside your house.

Check out our review of the BMW 4 Series Convertible. For more options, check out our list of the best convertibles on sale.

Mercedes C-Class Cabriolet vs BMW 4 Series Convertible – styling

Aside from the obvious changes to the roof, both cars look almost identical to the Coupe versions on which each is based. The Mercedes makes use of a traditional fabric roof and is shaped to look as similar as possible to the C-Class Coupe. The roof is finished in black as standard but buyers are also offered a choice of dark brown, dark blue or dark red. The electrically-operated design takes 20 seconds to open or close and can operate at up to 30mph.

BMW on the other hand has taken a different approach for its convertible. The 4 Series makes use of a retractable metal design. Though heavier than a fabric roof and less elegant in its appearance, it carries obvious benefits to security when closed – we’ve not tried them back-to-back but we don’t think the BMW’s metal roof will afford it any extra refinement over the well-insulated Mercedes. At 20 seconds, the BMW’s roof operation takes a similar time to the Mercedes, but only works at speeds of up to 11mph.

Mercedes C-Class Cabriolet vs BMW 4 Series Convertible – interior

Much like the rest of the C-Class range, the Cabriolet’s cabin is very easy on the eye. Three ringed air vents sit beneath a tablet-like infotainment screen in the centre console, which can be trimmed in a range of high quality finishes. There’s room for four, with roof-up headroom 12mm more generous in the back than in the Coupe.

The 4 Series dashboard isn’t quite as inspiring to look at, though it feels suitably sporty from the driver’s seat. The main issue is that much of the switchgear seems lifted directly from BMW’s other models while the Mercedes feels more bespoke. The BMW iDrive infotainment system, however, is vastly superior to Mercedes’ somewhat clunky setup. Much like the C-Class, everything is very well screwed together, too.

With the roof in place, the BMW has the marginally bigger boot – 370 litres to the Mercedes’ 360 – but the bulkier metal design means that figure drops to 220 litres when it’s stowed away. In contrast, the Mercedes loses a more modest 75 litres, while split-folding rear seats allow larger items to be carried, too.

Mercedes C-Class Cabriolet vs BMW 4 Series Convertible – driving

Thanks to the addition of roof reclining mechanisms and chassis bracing to compensate for losses in stiffness, both cars weigh noticeably more than the coupe variants on which they’re based. This dulls the driving experience fractionally, though few buyers are likely to notice the difference.

Optional air suspension sees the Mercedes pull ahead in terms of comfort. Drivers are able to select from a range of driving modes to alter the suspension’s behaviour to best suit the current road – though full comfort mode always seems to produce the best balance of compliance and control.

Even with the roof down, the Mercedes’ refinement is impressive. A low drag coefficient helps to reduce buffeting and wind noise and passengers’ hairdos are protected thanks to Mercedes’ Aircap system. Vents mounted in the top of the windscreen frame deflect air away from the cabin helping to keep things calmer within. Heated vents mounted in the headrests – known as Airscarf – allow C-Class Cabriolet drivers to benefit from top-down motoring on cold days, too. Best of all, Aircap and Airscarf are fitted as standard across the range.

One criticism aimed at the 4 Series Convertible is that occupants are a little too exposed to the wind with the roof folded. Fortunately, roof-up refinement thanks to the metal shell is great.

The BMW offers a generally good balance between ride and handling but, surprisingly considering the brand’s reputation, doesn’t handle as well as the Mercedes. Most problems revolve around the steering that doesn’t feel as connected as the Mercedes but, considering it also doesn’t ride as well as the C-Class, it loses out on this front, too.

Mercedes C-Class Cabriolet vs BMW 4 Series Convertible – engines

The C-Class Cabriolet is offered with a range of four and six-cylinder engines, fueled by either petrol and diesel. The range opens with the C180 – a 1.6-litre turbocharged petrol producing 154hp. Three 2.0-litre petrols follow, offering between 181 and 241hp. One six cylinder option – the range-topping C 43 AMG – transfers its considerable 362hp to the road via all four wheels.

Two variants of the same 2.1-litre diesel are available, producing either 168 or 201hp. The pair are capable of a claimed 62.8mpg and 61.4mpg respectively. While they’re more frugal than the petrols, they do sound a little gruff, which isn’t really in keeping with the character of a car like this. All C-Class Cabriolet variants are available with a seven or nine-speed automatic transmission.

The BMW doesn’t quite offer the same wide selection as the Mercedes under the bonnet, but three petrol and three diesel units means that there are still plenty to choose from.

Equipped with BMW’s 190hp 2.0-litre diesel, the 420d is the most frugal choice that either of the pair can offer – depending on wheel size, it’ll achieve as much as 64.2mpg in official tests. The pair of petrol units are very smooth and refined, but weighing as much as 295kg more than the equivalent 4 Series Coupe compromises the performance heavily. Like the Mercedes, selected models are available with four-wheel drive, adding an extra £1,500-£1,535 to the asking price, depending on model.

The ultimate performance choice between the two remains the M4. Its twin-turbocharged straight-six offers up 58hp and 22lb ft of torque more than the C 43 AMG and, as a result, it can sprint from 0-62mph in 4.4 seconds – 0.4 seconds quicker than the Mercedes. That said, an even more powerful AMG C63 model is on the cards for the future.

Mercedes C-Class Cabriolet vs BMW 4 Series Convertible – value for money

An entry-level C-Class will set you back £36,200 – marginally more than the 4 Series. The high cost is, however, offset by the respectable standard equipment that includes the desirable Aircap and Airscarf.

Both cars offer satellite navigation as standard and, while LED headlights are also included with the Mercedes, they’re a £1,600 option for the BMW.

Mercedes C-Class Cabriolet vs BMW 4 Series Convertible – verdict

On paper, it looks like the Mercedes C-Class Cabriolet is going to put up a very tough fight for the BMW 4 Series Convertible. It’s more stylish – roof up or down – and is easier on the eye from behind the wheel, too.

Best of all, the multi-layer fabric roof has already proven to offer coupe-like levels of refinement elsewhere in the Mercedes range, and the Aircap system means that it’s more comfortable than the 4 Series when the sun is out, too.

The BMW is the car to have if you want the ultimate straight line speed of the M4, and the diesels are slightly smoother and more frugal but, otherwise, it looks like the Mercedes might be the better choice for most buyers.

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Check out our review of the Mercedes C-Class Cabriolet or BMW 4 Series Convertible for the latest information. Alternatively, check out our car chooser to see what rivals have to offer.