The new models mark a shift from BMW M's naturally aspirated, revvy past to a new turbocharged era – but does this mean the company has sacrificed its renowned razor sharp throttle response for the sake of economy?
The new powerplant is a twin-turbo inline six making 317 kW and 550 Nm of torque from just 1850 rpm. While the power figure isn’t a big jump from the old car’s 309 kW, the new motor should have a very different character to the E92 M3’s naturally aspirated V8, which made all of its power at the top of the rev band. It was very exciting on a racetrack and thrilling when you were flat out, but was also no good for the economy targets set out by the EU. BMW is claiming a combined fuel economy figure of 8.8 liters per 100 kilometers (26 mpg) for the manual and 8.3 for the dual clutch auto. The old car could only manage 12.4.
Beyond the powertrain, there is some fascinating tech lying beneath the skin of the new M4. Carbon fiber has featured in previous M3s: the E92 M3 featured a carbon fiber reinforced plastic (CFRP) roof, as did the M4 coupe concept shown at Pebble Beach last year. The new M4 carries the lightweight roof over and adds a CFRP boot lid and strut brace to the mix, which helps to lower kerb weight to 3585/3530 lbs for the auto and manual respectively. The carbon fiber parts also lower the car’s center of gravity, making direction changes flatter and faster. But the M4’s real party trick comes in the form of the carbon fiber propshaft connecting the engine to the rear wheels. The new set-up takes advantage of the inherent lightness and strength that comes with carbon construction, and the car should enjoy better throttle response, not to mention the weight saving over a conventional steel unit.
The M4 isn’t the first car to use this kind of propshaft. The Shelby GT500 has a similar set up, but the throttle response benefits are likely to be more noticeable in the M4’s turbocharged engine, hopefully minimizing turbo lag. The propshaft also aids crash performance, as it will collapse in a controlled way when enough force runs through it.
Performance-wise, this translates to a top speed of 250 km/h (156 mph) and a 0-100 kn/h (0-62 mph) time of acceleration of 4.1 seconds for the manual and 3.9 seconds for the auto.
Much of the tech on modern performance cars is based around weight saving, and along with the carbon fiber componentry the M3/4 features lightweight aluminum forged wheels and optional carbon ceramic brakes. The brakes give the car plenty of track cred, although it remains to be seen whether they will suffer the lack of feel that is often noted with carbon ceramic set-ups.
As will be available on all of its competitors, the M4 can be fitted with adaptive dampers, which can be configured along with steering weight and gearbox shift speed from the optional seven-speed dual clutch gearbox. Thankfully for those of us who enjoy changing gears ourselves, BMW also offers a six-speed manual option. Drivers are able to choose from three pre-programmed drive modes, or save their own combination of gearbox, steering and damping settings to the “M” button on the steering wheel.
All of this, of course, is theoretical. BMW’s M cars carry a reputation for being some of the sharpest drivers cars around, so for all the new tech it’s carrying the M4 will need to drive exceptionally well. All the technical advancement in the world means little if the new M4 doesn’t handle like the old car. After all, what is an "M" car that can’t go around corners?
It's a question where looking forward to answering.
Pricing for the new M models starts at US$62,000 for the M3 sedan, and $64,200 for the M4 Coupe.