BMW 4 Series Convertible review

The BMW 4 Series Convertible is the soft-top model in the 4 Series range, which in turn is the two-door version of the 3 Series. The 3 Series and 4 Series feature many of the same engines and share many parts, despite the fact that they look very different from the outside.

A stand out feature of the 4 Series is the huge grille, and whether you love it or hate it, it’s currently the only option for those wanting a 4 Series. The distinctive look is much more eye-catching than the Audi A5 Cabriolet, which retains the more subtle design of its coupe sibling.

The 4 Series Convertible now has a fabric roof in place of the heavier folding hard top of the previous generation. BMW claims that new roof technology makes the soft-top just as quiet as the previous metal folding top when it's up, and that buyers now get more boot space. These claims held up in our experience, and the new roof folds away in just 18 seconds, at speeds of up to 31mph.

The interior of the 4 Series Convertible is very similar to that of the coupe, which means it’s packed with the latest tech and has high-quality materials that make it feel very upmarket – but you would expect that because the price is higher than ever. We particularly like the driving position, which is sporty and comfortable, and the fact that it’s still fairly quiet on the move even with the roof down.

There are plenty of engines to choose from, including three petrol and two diesels. The diesels are the 420d and 430d, along with the latest M440d offering 187bhp and 282bhp, and 345bhp respectively, while the petrol options are the 420i, 430i and M440i. These provide 181bhp, 242bhp and 369bhp respectively and are smooth, punchy and fun to use.

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The 4 Series is more fun to drive than its Mercedes and Audi alternatives, yet it also works really well as a comfortable cruiser. There aren’t that many four-seat convertibles available these days, so your choice is quite limited – but if that’s what you’re after, the new 4 Series Convertible should be on your shortlist.

In general, convertible cars aren’t known for their fuel economy. In fact, since they are usually heavier than hard-top models (they require extra strengthening because of the soft roof), convertibles are generally more expensive to run than coupes – and that’s true with the 4 Series, although it’s not by a huge amount.

The range starts with the 420i model, which has a 2.0-litre petrol engine. It returns 41.5mpg and emits 154g/km of CO2, so it’s a good all-rounder. The 420d diesel is more economical, at 57.6mpg and 129g/km of CO2, but it’s a bit noisier and isn’t great for local trips.

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The next step up in power is the 430i and 430d, returning 40.4mpg and 52.3mpg. Although they may not be able to match the entry-level version for efficiency, the added power provides smooth acceleration, and the diesel 430d boasts BMW’s traditional six-cylinder configuration.

The M440i is the model to go for if you are a keen driver and don’t mind the running costs, because it features tweaked suspension to make it more fun to drive – it’s more enjoyable than a Mercedes-AMG C43 Cabriolet in corners and it can go from 0-62mph in just 4.9 seconds, so it has plenty of performance.

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That’s thanks to a six-cylinder engine with 369bhp, so it also sounds great with the roof down and it has a slick and fast-shifting eight-speed automatic gearbox. Despite its racy performance the M440i is comfortable on long trips – and that’s true of all models because the soft-top roof provides a good amount of sound-deadening and there’s not too much buffeting from the wind with it down, either.

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If you’re tempted by the power of the M440i, but want more manageable running costs, the M440d is a diesel alternative. This engine produces nearly as much power at 345bhp, and can cover the 0-62mph benchmark in the same time as the M440i. The downside of that frugal yet powerful engine is weight, here the M440i has the advantage.

All 4 Series models have comfortable suspension, although it is stiffer in sportier specifications and reduces some of the suppleness of the mid-range models. If you plan to use the car for cruising then the 420i and 430i are two of the best choices, however if you like to take your car further afield, the 420d and 430d are better options.

The 4 Series Convertible is the best four-seat convertible to drive at this kind of budget.

The new soft-top roof replaces a folding hard-top that was on the previous 4 Series Convertible, but it’s just as quiet inside with the roof up, and the car is lighter overall. It’s quicker to take down – it takes 18 seconds at up to 31mph – and there’s a bigger boot as a result.

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The interior is taken from the 4 Series coupe and that means it’s excellent – the materials are high quality, the seats are comfortable and there’s lots of tech on board. There are extras here, too, including optional vents on the headrests designed to keep your neck warm with the roof down in cold weather.

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The infotainment is the same as in the 4 Series coupe, which means it’s easy to use, looks modern and has lots of useful features. There are online services for the sat-nav, a simple dial-based control system and a screen in place of traditional dials behind the wheel, which can display sat-nav directions and more. It’s all very smart and works well.

The new soft-top roof means there’s more room in the back of this version of the 4 Series Convertible. There’s now 385 litres of boot space, which is about the same as in an average family hatchback – although there are only 300 litres when the roof is down, because it is stored above the luggage area when folded away.

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This means the 4 Series Convertible isn’t as practical as the Audi A5 Cabriolet, but it’s still reasonable for a convertible car. The rear seats are a little cramped, as with many cars of this type; adults won’t want to sit there for too long because legroom is limited.

BMW came 16th overall in our Driver Power customer satisfaction survey, so while it didn’t manage to break into the top 10, it’s a steady improvement on the year before that puts it ahead of Audi (22nd) and Mercedes (23rd).

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However, the 4 Series Convertible uses engines and other parts from the 3 Series saloon, so parts availability is good and the engines are tried-and-tested in these other models. The 4-series performed well in its Euro NCAP crash testing.

Standard safety kit includes Active Guard Plus, which adds lane departure warning, autonomous emergency braking and front collision warning. You also get parking assist with sensors and a rear-view camera.