The revered BMW E39 M5, widely recognized for its high-performance V8 engine, very nearly adopted a different powerplant, a fascinating detail uncovered during BMW North America's 50th-anniversary commemorations. The predecessor, the E34 M5, featured a 3.8-liter six-cylinder engine that had reached its developmental apex, prompting BMW to explore new options for the E39. Discussions centered on two primary choices: a V8 or a turbocharged six-cylinder. Alex Hildebrandt, the E39 M5 Project Leader, revealed that Karlheinz Kalbfell, then head of the M division, was inclined towards fuel efficiency, a challenging prospect with a V8 given its inherent fuel consumption. Turbocharging was also considered, yet at the time, it primarily boosted high-end power rather than mid-range torque, and it was a significant departure from BMW's traditional naturally-aspirated engines. Even a turbocharged V6 was on the table, which would have been even more radical for a brand known for its inline-six configurations. Ultimately, the V8 was deemed the most suitable engineering solution, culminating in the 394-horsepower S62 engine, famously paired with a manual transmission, cementing the E39 M5's legendary status.
The decision to equip the E39 M5 with a V8 engine proved to be a masterful stroke, contributing significantly to its acclaimed performance and handling. The vehicle could accelerate from 0 to 60 mph in a mere 4.8 seconds, demonstrating its straight-line prowess. However, its excellence extended beyond speed. Scott Doniger, a former M Brand Manager for BMW North America, highlighted the car's exceptional balance, noting that despite the V8's weight, the M5 did not feel front-heavy. Instead, it achieved a holistic performance package with outstanding handling, whether accelerating, braking, or cornering. The commercial success of the E39 M5 further validated this choice, with 9,198 units sold in the USA by the end of its production in 2003, underscoring the positive reception of its shift away from six-cylinder power. This foundational success paved the way for more ambitious engineering decisions in subsequent models.
The success of the E39 M5's V8 adoption set a precedent for future innovations, notably influencing the development of its successor, the E60 M5. The E60 M5, though considered by some as more imperfect, was distinguished by its sensational 5.0-liter V10 S85 engine, a direct inspiration from BMW's Formula 1 racing expertise. This engine delivered 500 horsepower and revved to an astonishing 8,250 rpm, once again revolutionizing the M5's performance benchmarks. While the E60 faced challenges with complex technologies and reliability concerns, its daring V10 engine underscored BMW's willingness to push engineering boundaries. It is clear that without the critical technical leap made with the E39 M5's engine choice, BMW might not have ventured into the bold territory of a V10 for the E60, showcasing an enduring spirit of innovation and the pursuit of automotive excellence. The journey of the M5 series exemplifies how thoughtful engineering decisions, even those born from challenging debates, can lead to iconic automotive achievements and inspire subsequent generations of groundbreaking vehicles.