Hermann Bohrer, the director of the BMW plant in Munich, is a car manufacturing specialist with many years of experience. Building cars is his everyday job, but when the conversation turns to the new M4 Coupe, Bohrer turns out to be a real enthusiast.
“It’s a real drivers’s car,” he beams.
Bohrer’s passion for the M4 isn’t limited to the car itself. He’s also excited about F82 M4 production, which started at his Munich plant in May 2014 alongside the new 4 Series Coupe. The occasion marked the return of M car production to Munich for the first time since 1992, when the last of nearly 18,000 E30 M3s left the factory.
“There are still quite a number of employees with us who were involved in the production of the E30 M3, the first M generation, between 1986 and 1991,” Bohrer says. “They are very proud of the return of a legend.”
Subsequent generations of the M3—the E36, E46 and E9X—were built two hours up the autobahn in Regensburg, where the F80 M3 is now being built alongside the standard 3 Series. Manufacturing M models alongside the standard cars requires exceptionally efficient production processes and logistics, but it allows the plant to react quickly to market fluctuations by adjusting the production volume for each model. BMW has long done exactly that with cars that were fairly similar to one another, and the integration of a high-performance sports car into the manufacturing process “is a proof for the high flexibility of our production structures,” says Bohrer.
Last year, BMW invested almost €150 million in its production facilities, including the manufacturing infrastructure for the new M4 Coupe. It’s the first time that the Munich plant has built a car designed around a lightweight concept, and which incorporates an aluminum hood and side panels, a CFRP (carbon fiber reinforced plastic) roof and trunk lid. The bonding system for the carbon roof is also new to the plant.
The M4 uses 1,500 parts unique to the model, and the labor involved with its assembly is about 10% higher than for a regular 4 Series. It starts in the body shop, where workers fit the M4’s aluminum axle mounts, modified suspension mounts and additional stiffeners. In final assembly, the M4 gets its own sport suspension, steering wheel, seats and forged alloy wheels, plus the S55 turbocharged six-cylinder delivered from the BMW engine plant in Steyr, Austria.
Since the employees at Munich had never worked with lightweight construction, they relied on information and expertise shared by their colleagues from Regensburg, where the vehicles used in BMW’s motorsport activities are built.
The BMW plant in Landshut, a small town about an hour northwest of Munich, contributes some of the parts used in the M3s and M4s being built at Regensburg and Munich. Landshut serves as BMW’s “competence center” for lightweight technologies, and it produces the carbon fiber roof used in some 80% of M3s and M4s—the exceptions being those cars ordered with a steel sunroof. (Interestingly, the take rate on sunroofs is neatly reversed on the “regular” BMW models, about 80% of which are ordered with the retractable roof.)
The lightweight carbon roof is installed by hand by four employees specially trained for the task, which takes place in a separate workstation off the main assembly line. Every M4 is diverted for eight minutes so that those employees can sand the surfaces of the body’s roof frame and apply the adhesive, a process that’s photographed and documented for each car. Then a robot fits the roof and the employees check the result closely.
“It is a tricky operation where nothing should go wrong,” says Bohrer. And if something does go wrong, there’s no way to fix it, he says, pointing at the zero-tolerance space in which the roof has to fit.
The carbon roof is made by BMW, but the company works closely with its suppliers for a variety of other parts in aluminum, plastic and carbon fiber.
“Whether we buy or produce parts in-house is mainly a decision based on volume,” explains Michael Wimbeck, project leader for the M3 and M4. Right now, about 60 M4s are being built per day, which precludes making its most complex and costly parts in-house.
About half of the M4’s total production will be exported to the U.S., which is the largest market for BMW’s M cars, followed by the U.K. and Germany.
“China is growing, too,” says project leader Wimbeck.
In China, M cars account for less than 1% of BMW’s sales volume, but they’re more important there than the numbers suggest. China isn’t lacking for enthusiasts looking for relatively discreet supersports machines like BMW’s M cars, and they’re willing to pay big money to get them: Special editions of the M5 and the M6 have fetched the equivalent of up to $458,000, far more than they can command in either Europe or the United States.
They may be relatively understated, these M cars, but they’re not cheap!