The Mercedes-Benz M272 engine, a V6 powerplant, shares its 90-degree block architecture with its V8 siblings. This design choice was strategic, streamlining production processes and leveraging existing manufacturing infrastructure. Effectively, this V6 is conceived as a shortened V8, a testament to efficient engineering within Mercedes-Benz.
However, this 90-degree V-angle in a six-cylinder configuration presents a unique engineering hurdle. For a six-cylinder engine to achieve evenly spaced power pulses throughout the 720-degree four-stroke cycle, ideally, a power stroke should occur every 120 degrees. A conventional crankshaft in a 90-degree V6 engine would result in uneven firing intervals of 90-150-90-150-90-150 degrees. This uneven firing order can lead to undesirable vibrations, particularly at low to medium engine speeds (RPM), and introduce undue stress on engine components.
To counteract this inherent imbalance, the Mercedes M272 Engine incorporates a clever solution: a 30-degree offset on its crankshaft journals. This innovative design ensures the desired 120-degree firing stroke spacing, resulting in smoother operation. Furthermore, to mitigate secondary and tertiary order vibrations, the M272 employs a balancer shaft. This shaft rotates at crankshaft speed but in the opposite direction, effectively cancelling out these vibrational forces and contributing to the engine’s refined character.
Beyond this core balancing technology, the Mercedes M272 engine boasts other advanced technical features designed to enhance performance and efficiency. Continuously variable intake and exhaust valve timing, adjustable by up to 40 degrees, optimises engine breathing across the RPM range. This system, often referred to as variable valve timing (VVT), allows the engine to adapt to different driving conditions, improving both power delivery and fuel economy.
Another notable feature is the two-stage variable length intake manifold. At lower engine speeds, a longer intake tract is beneficial. This longer path helps to increase the momentum of the incoming air charge, improving cylinder filling and low-end torque. Conversely, at higher RPMs, intake friction becomes a more significant factor. In this scenario, a shorter intake path is advantageous, reducing resistance and allowing for greater airflow into the engine, thus maximising high-end power.
So, what is it like to experience the Mercedes M272 engine in action? The M272 is characterised by its eagerness to rev and its inherent smoothness. Peak torque is delivered at 5000 rpm, but a substantial portion of this pulling power is readily available from as low as 2500 rpm. This broad torque curve ensures responsive performance across a wide range of driving situations. The engine maintains its torque output effectively at higher RPMs, allowing peak power to be realised at 6000 rpm.
Below 3000 rpm, the engine operates with a subdued sound profile, with minimal induction or exhaust noise. However, as the revs climb, the engine’s aural character transforms, developing a pleasing and refined engine note. In models like the SL, especially when paired with the 7G-Tronic gearbox, engaging acceleration becomes readily accessible above 3500 rpm. For everyday cruising and keeping pace with traffic, however, the engine rarely needs to exceed 3000 rpm, highlighting its relaxed and efficient nature in normal driving.
The 7G-Tronic transmission, capable of downshifting two gears at a time, ensures that near-instantaneous acceleration is always within reach. While the automatic gearbox is highly responsive, some drivers may prefer to manually downshift, aiming for around 4000 rpm before applying full throttle. This technique is perceived by some as being gentler on the gearbox’s clutches and brake bands. Regardless of approach, the Mercedes M272 engine maintains its composure, never sounding strained or harsh, and pulls strongly beyond 6000 rpm, consistently building power. For what is often considered the entry-level powerplant in models like the SL, the level of performance and “shove” delivered is often surprising.
The Mercedes M272 engine is an engine that grows in appreciation over time. It possesses a distinct character that sets it apart from other engines in its class, even outshining some supposedly more charismatic units. Comparisons can be drawn to engines like the 360-bhp V8 found in certain Audi S8 models and even the 2.7-litre biturbo in the RS4, which some perceive as less refined and harsher in sound. In terms of real-world running, anecdotal evidence suggests the M272 is robust and reliable. Using a quality synthetic oil such as Mobil 1 0W40, oil consumption is typically minimal to non-existent. Fuel economy is respectable for its class and performance, with figures reaching as high as 35 mpg on gentle runs, although 25-30 mpg is more typical in mixed driving conditions, especially considering the weight of vehicles like the SL.
In conclusion, the Mercedes M272 engine is a well-engineered and rewarding powerplant. Its blend of technical innovation, smooth performance, and surprising character makes it a highly likeable engine that delivers a satisfying driving experience.
