BMW 4 Series Convertible
“The BMW 4 Series Convertible is nearly as practical as the coupe on which it's based, yet provides the bonus of wind-in-the-hair thrills”
- Good range of engines
- Quiet interior
- Secure folding metal roof
- Could be more fun to drive
- Heavy roof harms performance
- Coupe has more rear headroom
The BMW 4 Series Convertible is the replacement for the BMW 3 Series convertible. With lots of space in the front seats and enough room for kids or taking adults on short trips in the back, it’s a stylish convertible without all of the compromises of an out-and-out sports car like the BMW Z4.
Like the rest of the 4 Series range, the Convertible has benefitted from some mid-life changes, although you’d be hard-pushed to tell from the outside. Larger air scoops in the front bumper and twin LED headlights are the biggest changes, but it faces stiff competition from the stylish Mercedes C-Class Cabriolet and Audi A5 Cabriolet in this department.
Under the metal, the engine line-up has been expanded and its suspension has been tweaked to improve steering feel. In contrast, the number of trims on offer has been simplified by removing the SE and Luxury grades, leaving just Sport and M Sport.
As with the old model, the BMW 4 Series Convertible gets a convertible metal roof that means it has a quiet interior and added security over fabric-roofed rivals. Unfortunately, it makes the convertible quite heavy – so it’s not quite as much fun to drive as the 4 Series coupe it’s based on. That said, when you fold back the roof, not much can compare for luxurious wind-in-the-hair thrills.
The BMW 4 Series Convertible can be fitted with a 3.0-litre petrol engine (for impressive pace), two smaller petrol engines that are quick and economical, or a range of diesel engines providing excellent performance while being more economical than the petrols.
The BMW 4 Series finished 22nd out of the 75 cars ranked in our 2017 Driver Power owner satisfaction survey of cars currently on sale in the UK. The 4 Series itself hasn’t been crash-tested by the independent experts Euro NCAP, but the BMW 3 Series it’s based on achieved a five-star rating.
MPG, running costs & CO2
The most economical BMW 4 Series Convertible is the 2.0-litre diesel badged as the BMW 420d, which is capable of 56.5mpg and CO2 emissions of 138g/km. Benefit-in-Kind (BiK) tax liability is 28%.
A more powerful diesel version badged 435d returns 44.1mpg and emits 169g/km of CO2 despite its increased performance – even with the addition of BMW’s xDrive four-wheel-drive system.
All figures given for the diesel engines above are measured using the latest real-world testing system (known as WLTP), meaning they should be more achievable in daily use than those previously quoted.
The petrol range starts with the BMW 420i, capable of up to 42.8mpg and CO2 emissions of 153g/km for a 29% BiK band.
The 2.0-litre BMW 430i petrol offers a halfway house between the diesel and the top-of-the-range 3.0-litre petrol. It can return 40.4mpg and emissions of 162g/km, but is quite a lot faster than the diesel.
Fastest model of all, though, is the 3.0-litre BMW 440i petrol. However, while it’s very quick, you're unlikely to manage more than 30mpg, even if the official figure is 39.2mpg.
After the first year's CO2-based road tax (generally included in the on-the-road price), all BMW 4 Series cost £140 a year to tax. Those with a list price (including options) of more than £40,000 are liable for an additional surcharge of £310 a year in years two to six, bringing the annual bill to £450 during that period.
Engines, drive & performance
The BMW 4 Series Convertible weighs quite a lot more than the BMW 4 Series coupe thanks to the car’s complicated roof system. That has the effect of dampening performance and handling, making it more of a comfy cruiser than a sports car when cornering – with more body lean and slightly slower acceleration.
For 2017, the steering feel and suspension were improved and while the 4 Series Convertible still isn’t as sharp as the coupe, it’s the best driver’s car in the class.
Even the diesel version’s 2.0-litre engine produces 187bhp, meaning acceleration is impressive enough – taking 8.1 seconds to get from 0-62mph. That’s nearly a second slower than the diesel coupe, but two tenths faster than the Mercedes C220d Cabriolet and never feels sluggish. The 420i takes 8.2 seconds to do the same, while the 430i is quite a lot quicker, getting from 0-62mph in 6.4 seconds.
The BMW 440i gets a 3.0-litre petrol engine that produces 322bhp. It goes from 0-60mph in 5.4 seconds and has a top speed of 155mph. The 440i isn’t quite the fastest version, though, because the 435d xDrive uses its four-wheel drive to good effect, catapulting from 0-62mph in 5.2 seconds, which is seven tenths faster than the rear-wheel-drive 430d.
Interior & comfort
Inside, the BMW 4 Series Convertible shares much with the 4 Series Coupe that it's based on. So it gets a high-quality, logical-to-use and well built dashboard with BMW’s iDrive infotainment system, which is easy to use and very effective on the move. The driver’s seat also has plenty of adjustment, which means it's easy to get comfortable.
The folding metal roof on all BMW 4 Series Convertible models means that interior noise is kept to a minimum – and makes the car harder to break into. The BMW 4 Series can also be specced with BMW’s Air Collar, which directs hot air to the back of your neck, to counteract the cold draft caused by having the roof down.
Changes for the facelifted model are slight, but include a new electroplated finish for some interior trim, including the switch for the folding roof. Stitching around the instrument panel, a new wrap for the steering wheel and improved switches for the climate control all add to its appeal. In the end though, the makeover can’t compete with the more stylish interior found in the Audi A5 or Mercedes C-Class cabriolets.
Practicality & boot space
With the roof up, the BMW 4 Series Convertible is almost as practical as the BMW 4 Series Coupe. There’s plenty of space up front and legroom isn’t too bad in the rear, either. The front seats tip and slide forwards, so access to the back seats is pretty decent, too, although headroom is tight for anyone over six feet tall. That said, if you drive around with the roof folded headroom is unlimited.
The BMW 4 Series has a decent-sized 370-litre boot, which is 20 litres more than the old BMW 3 Series convertible. This drops to 220 litres with the roof down, though, making it less practical than the Audi A5 Cabriolet, which has a 380-litre boot with the roof up or down.
Reliability & safety
The BMW 4 Series was rated highly overall for reliability in our 2017 Driver Power owner satisfaction survey of cars currently on sale in the UK. Of the owners who responded, only 8.7% reported experiencing a problem with their car on one or more occasion.
The BMW 4 Series Convertible is also likely to be extremely safe. Although the model has yet to be crash-tested by Euro NCAP, the closely related BMW 3 Series got a five-star rating for safety. The 4 Series also gets safety features including ABS, braking assistance, stability control, and numerous airbags as standard, so we expect it to fare well in the event of a crash.
Price, value for money & options
The BMW 4 Series Convertible is expensive to buy, but you get a long list of standard equipment – even with the entry-level Sport trim.
All models come with front and rear parking sensors, heated seats (useful in the winter sunshine), cruise control, climate control and BMW’s iDrive infotainment system with sat nav. The handy iDrive controller is easy to use, and governs all the car's functions from sat nav and radio, to the Bluetooth phone connection and settings.
The M Sport version has more aggressive styling and chrome tailpipes, along with LED exterior lights. The interior gets a makeover, too, with a different set of dials, black headliner and items like a sports steering wheel and pedals. For 2018, 'remote services' are fitted as standard, letting owners check things like how much fuel is left in their car, and even set its ventilation or unlock the doors, all from a smartphone app.
Options include the BMW Professional Plus media pack with enhanced sat nav and a clearer display, along with a head-up display (that projects information onto the windscreen) and online services. The M Sport Plus pack adds 19-inch alloy wheels, upgraded brakes, auto-dipping headlights and an upgraded stereo with 16 speakers.