The 4 Series uses a variety of engines from the 3 Series. These stretch from the entry-level four-cylinder diesel, the 420d, right up to the potent turbocharged six-cylinder petrol in the 440i and M4.
The 420d has the broadest appeal. It's relatively swift and revs keenly for a diesel, with good flexibility when you need a quick surge of power to overtake. If you want a higher-performance diesel, the 4 Series presents two highly capable candidates in the 430d and 435d, the latter being available only with four-wheel drive.
The only engine in the range to avoid is the 420i petrol, which revs quickly enough but simply can’t match the in-gear response of the diesels; it has to be worked hard to make reasonable progress. The turbocharged 3.0-litre petrol in the 440i, meanwhile, pulls strongly from very low revs all the way through to 7000rpm; it feels extremely quick and makes overtaking effortless, and is definitely the pick of the petrols.
The pinnacle of the range is the high-performance M4. This has a twin-turbocharged straight-six engine with more than 400bhp, can go from 0-62mph in close to four seconds and has a huge number of bespoke parts to save weight and improve its handling.
Like most BMWs, the 4 Series comes with the option of adaptive M Sport suspension, which can be adjusted to suit different roads and driving conditions. Cars fitted with these dampers strike a fine balance between ride comfort and agility. You can choose between Sport mode (for a stiffer ride but better road holding), Comfort and Comfort+, which softens everything for a more compliant but still well-controlled ride.
On standard passive dampers, the 4 Series is a little less able to react to changes in the road surface, so lumps and potholes are felt as heavier thumps inside the car. It's therefore best to stick with smaller alloy wheels if you have the standard suspension. Even on adaptive dampers, the optional 19in wheels still send a few thuds through your seat when travelling over rough roads.
The exotic M4, with its standard 19in wheels and bespoke tyres, has a much firmer ride than any other car in the range, but its high-quality damping means it’s never uncomfortable.
Of all the executive saloons, the 3 Series is one of the very best to drive. And its two-door cousin here is even better, feeling more composed than the 3 Series in corners, thanks to its lower centre of gravity and wider stance.
The steering is accurate and responsive, making the 4 Series easy to place on the road. It offers more feedback than, say, the Audi TT's, while the car's rear-wheel drive layout gives it a real feeling of delicacy in corners. Probably the best part of the handling, though, is that this agility does not come at the expense of comfort. The 4 Series doesn’t float or bounce over bumps, treading a fine line between comfort and control.
There is one caveat, though; the 4 Series is a bit wider than some coupés, so it can feel a bit ungainly on narrow roads.
The six-cylinder petrol engine in the 440i is a peach, making a bassy thrum that becomes a creamy howl when you rev it.
By contrast, the 2.0-litre diesel in the 420d sounds gruff – a trait that you can’t fail to notice on start-up or when accelerating. The six-cylinder diesels are a little more refined, but they still lag behind the most hushed cars in this class, such as the Audi A5 3.0 TDI.
The 4 Series suffers from a little too much wind and road noise at speed. This problem is also quite dependent on wheel and tyre choice; the bigger you go, the louder the road noise gets.
The standard six-speed manual gearbox has a springy yet accurate gait, but its clutch is quite heavy and there's often judder through the gearlever when pulling away. That’s why the optional eight-speed automatic gearbox is well worth considering, because it shifts swiftly and smartly and is more efficient and refined.
To emphasise the 4 Series' sporty character, its driver’s seat is mounted very low down, so you feel close to the road and more in touch with the car's agile underpinnings.
The steering wheel has reach and height adjustment and you can adjust the driver’s seat with a ratchet handle on the side of the seat. High-spec versions come with electric adjustment. Both front seats hold you firmly in place and are supportive, with thickly cushioned bolsters. The only small gripe you might have is with the offset pedals; they are noticeably over to the right, forcing you to sit at a slightly awkward angle.
The 4 Series' dashboard will be instantly familiar to any 3 Series driver, with a wide instrument panel and centre console, clear dials and a smart driver’s information screen.
Turning the 3 Series into a two-door has made the 4 Series harder to see out of, but the difference between the two cars is nowhere near as big as you might expect. A lower roof, thicker rear pillars and a smaller rear screen make the 4 Series' rear view trickier, but forward visibility is still okay.
Parking sensors front and rear are standard on all 4 Series models and a reversing camera is an option. If that’s not enough, you can opt for a bird's-eye-view camera and a self-parking system, too.
The 4 Series also offers the option of a head-up display, which projects key driving information onto the windscreen so that you never need to take your eyes off the road. You can pay extra for an auto-dimming rear-view mirror as well.
All 4 Series models get sat-nav, a DAB radio, Bluetooth and a USB port, while the steering wheel has audio and phone controls built in.
Every car gets the excellent iDrive infotainment system. It’s linked to a 6.5in screen (if you specify Sport trim) and is controlled via a handy rotary dial by the gearstick that's simple to use. And it’s easy to see the screen because it's mounted high up on the dash. You can upgrade the system with optional smartphone mirroring, connected apps and online web browsing services.
Opt for the Professional Media Package (standard on M Sport trim) and you’ll get an 8.8in screen, an even greater number of online services and an upgraded sat-nav. The system remains just as easy to navigate and is stuffed with features.
While the 4 Series' interior isn't as solid or well finished as the Audi A5's, the materials are still pretty sumptuous, the fit and finish is decent and most of the switches work with a solid and reassuringly positive action.
Choosing a higher trim will bring better finishes, including gloss black surrounds on the centre console and sporty red inserts across the dashboard – or you can choose aluminium or carbonfibre trims, if you wish.
Drivers of all shapes and sizes will be comfortable behind the wheel of the 4 Series. There's plenty of shoulder room and it feels roomier than its coupé rivals such as the Audi TT and Porsche 718 Cayman. However, the centre console is a little cluttered when compared with, for example, that in the Mercedes-Benz C-Class Coupé – and this problem is made worse in 4 Series models with a manual gearbox and manual handbrake.
There’s a decent amount of storage space, though, with wide, teardrop-shaped door pockets. Extra cubbyholes can be found under the wide central armrest and there’s a pair of cupholders. The 4 Series also comes with a plastic insert that covers this space to double up as a coin tray for loose change. The glovebox is a reasonable size, too.
This is the area where most coupés fall short, but the rear seats of the 4 Series are far from being a token gesture towards practicality. Passengers can get in easily enough, thanks to the wide doors and front seats that slide far forward and out of the way.
Once inside, there's a surprising amount of leg room, but the sloping roof means taller passengers will have to slouch to stop their heads from brushing the roof. There’s room for only two, with the space between them given over to an armrest.
There isn’t much storage space in the back, with no cupholders or door pockets, but even so the 4 Series is more practical than most of its rivals.
As standard, the 4 Series' rear seats split-fold 60/40. Once folded down, the rear seatbacks sit at a slight angle rather than fully flat, and the parcel shelf is fixed, so there's a restriction on the height of objects you can carry.
However, you can spend a bit extra for seats that fold 40/20/40, with a useful ski hatch through the middle for longer items.
The front seats automatically return to their original position, so the driver won’t need to reset them every time someone climbs into or out of the back. The seats themselves are easy enough to fold forward but can get caught on the rear seatbelts.
The 4 Series comes with a seatbelt extender, so you don’t need to reach back over your shoulder to buckle up when setting off. However, it’s odd that lumbar support for either front seat is not standard on any model.
Among saloon-based competition, the 4 Series Coupé's 445-litre boot is on a par with that in the Audi A5 and 45 litres greater than the Mercedes-Benz C-Class Coupé's boot. It's easily enough for a set of golf clubs or a couple of decent-sized suitcases. And it carries comfortably more luggage than coupés such as the Audi TT.
The boot's wide, square shape makes it relatively easy to load, but there is a deep lip, so heavier luggage needs to be dropped (rather than slid) in. With the rear seats down, there's even more room.
The 4 Series comes with the option of Comfort Access, a clever sensor that opens the boot when your hands are full – all you need do is wave your foot under the rear bumper.
Company car drivers and private buyers alike will be pleased with the running costs of the 4 Series.
For business users, the diesel versions are very competitive when it comes to CO2 emissions (and therefore company car tax), although the Mercedes-Benz C-Class Coupé is slightly better still.
Private buyers will like the 4 Series' strong residual values; it holds its value extremely well.
The automatic version of the 420d claims an official fuel economy figure exceeding 60mpg, while in our real-world tests it recorded a combined figure of 52.0mpg. Even the 440i is claimed to return a respectable 41mpg when paired with the auto gearbox, although we have yet to run out own tests on this model.
BMW offers competitive PCP leasing deals, often over a four-year period with a reasonable rate of annual interest and the option to buy the car at the end. The brand’s servicing plans are equally good value, with five years’ maintenance for the price that some companies would charge for a single interim service.
Part of the justification for the higher price of the 4 Series over its 3 Series sibling is that it’s better equipped. Indeed, even the entry-level Sport version comes with all-round parking sensors, heated leather seats, a DAB radio, brighter LED headlights and a multi-function steering wheel.
The M Sport model comes with a stiffer suspension set-up, although the firmer springs can be removed as a no-cost option. M Sport also features an aerodynamic bodykit, deeper air intakes in the front and rear bumpers and 18in alloy wheels. It is expensive, though, so you’re better off sticking with Sport trim and spending your money on a few choice options.
BMW’s reliability record is reasonable rather than outstanding – it finished solidly in the middle of the table (17th out of 32 manufacturers) in our latest reliability survey. Mercedes-Benz did worse, but Porsche and Audi both finished higher up in the rankings. The 4 Series finished an impressive second out of eight cars in the coupé class.
BMW offers a three-year unlimited-mileage warranty and, for total peace of mind, you can buy an insured warranty to keep your car covered for a few years longer.
Standard safety equipment includes six airbags and a sophisticated stability control system. There’s plenty of high-tech optional kit, too, including a system that warns you if you unintentionally move out of your lane.
Adaptive cruise control is another stress-reducing option, although it’s disappointing that this feature also includes automatic emergency braking, which should really be standard on a car costing this much.
While the 4 Series hasn’t been crash tested by Euro NCAP, we’d expect it to match the five-star rating of the 3 Series saloon on which it’s based.
An alarm system is standard across the range and the 4 Series scores highly in the Thatcham Research security tests, so it’s a difficult car to break into.
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