The new BMW 4 Series Coupé has been revealed with bold new styling that its design chief says represents "everything BMW should stand for", along with a focus on improving its dynamic performance.
The new styling is designed to further differentiate the two-door, four-seat coupé from the related 3 Series saloon.
The second-generation 4 Series will go on sale in October with a range-topping 369bhp M440i model before the M4 performance flagship follows late next year. Convertible and four-door Gran Coupé variants are in development, with a 523bhp i4 electric saloon also due in 2021.
The 4 Series launched as a stand-alone model in 2014, taking the baton from the three-door 3 Series. While it's based on the same CLAR platform as the latest 3 Series, BMW has substantially overhauled the design of the coupé. It features a sleek side profile with bold surfaces, the reduced use of some of BMW's traditional styling lines and narrow, and full-LED lights front and rear.
The most distinctive feature, though, is the large front grille, which uses a 'more vertical' interpretation of the signature kidney shape that's designed to invoke classic BMWs, such as the pre-war 328 sports car.
BMW design boss Domagoj Dukec told Autocar the bold grille is intended to make the 4 Series look "more emotional" and offset the reduced use of other key design elements.
"The kidney is our most prominent design icon," said Dukec. "We did so many things differently with this car: there's no horizontal shaven line, no classic Hofmeister kink. With so many things different in the body, we wanted a very special grille linked to our heritage.
"If you look at models like the 328, until the 1980s the grille was always more vertical than horizontal. We wanted a kidney with a strong link to our heritage – but it shouldn't look like any BMW before and it shouldn't look like any other car on the road."
At 4768mm, the new 4 Series is 128mm longer than its predecessor, with its wheelbase increased by 41mm to 2851mm – matching the current 3 Series.
While the coupé is just 27mm wider than before (at 1852mm) and 6mm taller (at 1383mm), its track has been increased by 28mm at the front and 18mm at the rear. Alloy wheel sizes range from 18in to 20in.
The 4 Series will go on sale with three petrol engines and one diesel. Two 2.0-litre four-cylinder petrols offer 181bhp (420i) and 254bhp (430i), while a 48V mild-hybrid 2.0-litre four-cylinder turbo diesel delivers 187bhp (420d) and official fuel economy of between 67.3 and 72.4mpg.
The range-topper will be the M440i xDrive, producing 369bhp and 369lb ft from a 48V mild-hybrid 3.0-litre six-cylinder turbo petrol engine. It's claimed to be capable of 0-62mph in 4.5sec, a top speed of 155mph and fuel economy of 39.8 to 41.5mpg.
Mild-hybrid six-cylinder diesels producing 282bhp (430d) and 335bhp (M440d) are due next March.
All engines drive through an eight-speed automatic gearbox. M Sport cars feature a Sport 'box that's optional on other models; in addition to quicker shifts, this brings launch control and a new driving mode named Sprint.
Rear-wheel drive is standard except on the M440i, 430d and M440d; four-wheel drive is also optional on the 430i and 420d.
BMW has worked to reduce weight with the CLAR platform through a mixed steel-and-alloy structure and increased use of aluminium panels, plus the chassis has been tweaked from the 3 Series on which it's based.
The 4 Series' wider rear track gives it a 21mm-lower centre of gravity than the 3 Series, and BMW claims a 50:50 weight distribution. An almost fully sealed underbody, new air flaps and other steps have reduced drag to as low as 0.25Cd.
BMW has also introduced a number of stiffening measures on the body and suspension mountings, along with double-jointed spring-strut front suspension and a five-link rear axle. Lift-related dampers are used to reduce body movement and improve cornering ability.
BMW says it has put a focus on the handling dynamics of the 4 Series, with increased damping and firmer springs and anti-roll bars. On standard suspension, the 4 Series rides 10mm lower than the 3 Series.
The optional Adaptive M set-up features electronically controlled dampers, while the M Sport differential is also available (standard on the M440i and M440d), along with variable-ratio steering.
The 4 Series' four-seat cabin features several familiar BMW design trends, with a reworked layout including the start button in the centre console beside a redesigned drive selector. The latest version of BMW's iDrive infotainment features, with a new, larger head-up display optional.
There are new sports seats as standard, while the folding rear seats split 40:20:40. The boot has a volume of 440 litres.
The 4 Series will be the first car to offer BMW's M Sport Pro package, which adds the Sport gearbox, a "sporting engine soundtrack" in Sport mode, M Sport brakes and new design trim, among other extras.
Prices start from £39,870 for the 420i M Sport (up £3670 on the equivalent 3 Series) and rise to £53,875 for the M440i.
Q&A: Domagoj Dukec, BMW design chief
Why make the 4 Series so different from the 3 Series?
"They're two products with different use cases: one is a family saloon, the other an expressive, sporty car. Customers pay more for a two-door coupé; it's not a pragmatic decision, so it needs a more expressive, emotional design. It's for customers who want to really show off."
Why make the grille so bold?
"It should be in the core of BMW to have a product which makes a strong statement. It's unmistakably BMW, unmistakably 4 Series. It's not just logical; it has a very strong character that's unique to our brand."
What did you make of the reaction to the grille on the Concept 4 Series?
"In design, you can't listen to social media reactions. Design is emotional, and everybody has an opinion and different taste. There's no right or wrong in design. "The criteria for design is to make something unique, something daring. I'm 100% convinced something like this, although polarising in the beginning, is at the heart of BMW and a brand-shaper for us. In two or three years, I'm convinced this will be a really strong product for us on the road."