BMW 4 Series Convertible review

We love a bit of innovation, but sometimes traditional methods are best – as demonstrated by the BMW 4 Series Convertible.

You see, after switching to a folding metal roof for the previous-generation car, this convertible variant of the BMW 4 Series has now returned to a good old-fashioned fabric one.

Why? Well, a soft-top takes up far less space. You could fit your luggage or the roof in the boot of the previous-generation car, but not both at the same time. The revised design fixes that. The 4 Series Convertible has also gained mild-hybrid engine technology, potentially improving efficiency and performance.

There are not really any direct rivals to this model at the moment, but if you're after some wind-in-your-hair motoring, you might also be considering the BMW Z4, the Porsche 718 Boxster or even the VW T-Roc Cabriolet.

So, how does the BMW 4 Series Convertible score against the best cabriolets for performance, interior quality, practicality and costs? Read on to find out...

The BMW 4 Series Convertible range kicks off with the 420i model, which uses a 2.0-litre turbocharged petrol engine producing 181bhp. It’s our pick in the BMW 4 Series Coupé and remains so here, because it should be brisk enough for most people and makes sense financially.

The convertible variant has to lug around 165kg more than the coupé, so the engine does have a harder time of it here. It takes a not particularly sporty 8.2 seconds to accelerate from 0-62mph and feels quite flat low down, so it's just as well that it's happy to rev.

For stronger performance, there’s the 369bhp M440i petrol. Power is sent to all four wheels to deliver whipcrack acceleration (0-62mph takes just 4.9sec) while making a more soulful noise.

To read about the fastest variant, see our BMW M4 Convertible review.

Whichever engine you choose, you get an automatic gearbox that makes slick changes, especially in Sport mode. You can take control yourself using the shift paddles mounted on the steering wheel.

Lopping the roof off a car often makes its structure rather floppy, and while you’ll see the 4 Series Convertible's rear-view mirror wobbling sometimes, it takes a big bump for any shake to come up through the steering column. Thankfully, the steering remains as precise as it is in the coupé, allowing you to place the nose of the car exactly where you want it.

If you go for the M Sport Pro Package or the M440i engine, BMW gives you M Adaptive Suspension.

That lets you stiffen or soften the ride by selecting different modes, and even Comfort mode does an excellent job of propping up the body during hard cornering. In fact, on pockmarked and uneven B-roads, Comfort is a better bet than the more focused Sport setting because its extra suppleness stops you from being bounced off course.

Whichever mode you select, the car has an agility that's surprising given its extra weight compared with the coupé, and a comfortable ride, even with big 19in wheels fitted. It rounds off all but the nastiest bumps and potholes, and deals with undulating tarmac with a great balance of comfort and control, making this a car you’d happily cruise around in all day. We’ve yet to try the standard suspension set-up but we’ll update this review when we do.

When it's in place, the fabric roof does an excellent job of keeping noise down, with only a bit of wind whistling from around the front windows. There's a fair amount of road noise filtering up through the floor, but the engines settle down when you’re not pushing on.

If you drop the roof of the 4 Series Convertible but keep the windows up, you won’t arrive at your destination looking like your hair has had a close encounter with a hurricane.

You can add an optional Warm Air Collar (as part of the Comfort Pack) – basically, vents in the front seats that blow warm air on to your neck. The removable wind deflector, which can be fitted over the rear seats, is worth considering to protect your hairdo.

Driving overview

Strengths Punchy engines; rewarding handling; comfortable ride on adaptive suspension

Weaknesses Some road noise at speed

When you're inside the 4 Series Convertible, you’d be forgiven for thinking you’d accidentally got into a BMW 3 Series. The driving position is almost identical, as are the dashboard and infotainment system.

In many ways, that's great news, because it means you get a comfortable and supportive driver’s seat with lots of adjustment, as long as you add optional adjustable lumbar support.

Forward visibility is good, with windscreen pillars that are slim enough not to get in the way at junctions.

Rear visibility isn’t great with the roof up because the rear headrests block much of the small rear screen, and there’s a lot of canvas obstructing your rear three-quarter view. At least front and rear parking sensors come as standard on all models, along with a rear-view camera.

All versions come with bright adaptive LED headlights, which can maintain maximum illumination without dazzling drivers ahead of you. 

Build quality is first rate, with only the odd bit of hard plastic and some silver-painted buttons on the dashboard letting the side down a little. 

The driver gets a 12.3in digital driver display as standard with all trim levels. It shows lots of information, and is positioned right beside a 14.9in central infotainment display in the same housing.

You can operate it as a touchscreen or by twisting and pressing a rotary controller between the front seats. Adjusting the temperature and climate control system is more fiddly than before (the latest facelift got rid of user-friendly physical buttons below the air vents), but the system is much less distracting to use while you’re driving than a touchscreen-only one.

The system also includes Android Auto and Apple CarPlay smartphone mirroring, along with a DAB radio and built-in sat-nav.

Wireless phone-charging is available as part of the Technology packs, as well as a punchy 464W, 16-speaker Harman Kardon sound system (available in Technology and Technology Plus packs, or as a standalone option).

Interior overview

Strengths User-friendly infotainment system; classy, high quality interior

Weaknesses None we’ve seen so far

Practicality isn’t going to be a top priority when buying a two-door soft-top like the BMW 4 Series Convertible, but the chances are you occasionally need four seats and a boot that can swallow more than just a shoe box.

There’s as much space up front for occupants in the 4 Series as you’d get in a BMW 3 Series so you’re unlikely to have any problems with head or leg room. That includes storage space as well, with a big glovebox and a decent cubby under the centre armrest.

There's a useful lidded storage area in front of the gear selector, where you’ll find a couple of generous cupholders and a space for your phone and keys. You also get partitioned door bins so loose items don't roll around.

Getting into the rear seats involves squeezing through a relatively narrow gap, but the same is true of all four-seat convertibles. Once you’re in, you’ll find acceptable leg room.

Taller adults will need to cower slightly or put up with their head resting on the ceiling, but a couple of six-footers will be comfortable enough in the back as long as the journey isn’t too long. BMW gives you a couple of cupholders back there, too, but the other storage areas are pathetically small.

The boot is slightly smaller than in the BMW 4 Series Coupé and – as with most convertibles – offers more space with the roof up than with it down.

There’s still space for up to six carry-on suitcases and you can fold down the rear backrest using a handy lever in the boot. Unlike in the coupé, the seats don't split and fold down for greater storage flexibility, but there is a cubby behind them where you can store the optional wind deflector vertically.

Practicality overview

Strengths Plenty of space up front for occupants and storage; the rear seats are a good size

Weaknesses Boot opening could be a touch wider; rear seats aren’t as versatile as the coupé’s

The BMW 4 Series Convertible costs slightly more than the equivalent 4 Series Coupé, but there are few direct rivals priced against it. The VW T-Roc Cabriolet is cheaper, but is nowhere near as sharp to drive.

The 420i petrol is a cheaper option if you're buying with cash or on PCP finance, and is predicted to hold on to its value better. Indeed, the model as a whole is predicted to hold its value against depreciation better than rival convertible cars.

Entry-level M Sport trim comes with plenty of standard kit, including 18in alloy wheels, leather seats (heated in the front), cruise control and three-zone climate control. In terms of options, it’s worth paying extra for adjustable lumbar support and the M Sport Pro Package, which adds adaptive suspension.

You could be tempted to upgrade to the M Sport Pro Edition model, because that includes the adaptive suspension as standard, along with 19in alloys and a choice of three exclusive colours, but we don’t think it's worth the extra cost. The range-topping M440i is similarly equipped to the M Sport Pro Edition, but gets the mighty six-cylinder turbocharged petrol engine.

The 4 Series Convertible didn't feature in the 2023 What Car? Reliability Survey but BMW finished in 12th place out of 32 brands.

The model was tested for safety by Euro NCAP in 2019 and received the full five-star rating. It scored well, partly thanks to the model's standard collision-prevention equipment, including automatic emergency braking (AEB) and lane-departure warning.

Buyers can also add the optional Driving Assistant Professional Pack, which comes as part of the Technology Plus Pack. That includes adaptive cruise control, a more advanced lane-keeping assistance system, a front cross-traffic alert system and automatic speed-limit assistance.

Costs overview

Strengths Generous level of standard equipment; high resale value

Weaknesses Plenty of tempting options could quickly drive up the price

For all the latest reviews, advice and new car deals, sign up to the What Car? newsletter here