The Mercedes-Benz M272 engine is a sophisticated V6 powerplant that shares its 90-degree cylinder block architecture with the brand’s V8 engines. This design choice was strategically implemented to streamline production processes, minimizing the need for extensive re-tooling in manufacturing facilities. Essentially, the M272 V6 can be viewed as a cleverly engineered, shortened iteration of its V8 counterparts.
A key challenge in V6 engine design, particularly with a 90-degree block, lies in achieving evenly spaced power pulses throughout the engine’s 720-degree four-stroke cycle. Ideally, a six-cylinder engine should deliver a power stroke every 120 degrees to ensure smooth operation. However, a conventional crankshaft in a 90-degree V6 configuration leads to uneven firing intervals, typically resulting in a sequence of 90-150-90-150-90-150 degrees. This uneven firing order can generate undesirable vibrations, especially at low to mid-range RPMs, and induce undue stress on engine components.
Mercedes-Benz engineers ingeniously tackled this issue in the M272 engine by incorporating a 30-degree offset on the crankshaft journals. This innovative crankshaft design is crucial in achieving the desired 120-degree firing stroke intervals, resulting in significantly smoother engine operation. Furthermore, the M272 features a balancer shaft that rotates at crankshaft speed but in the opposite direction. This balancer shaft effectively mitigates second and third-order vibrations, further enhancing the engine’s refinement and smoothness.
Beyond these fundamental design elements, the M272 engine boasts several other notable technical highlights that contribute to its impressive performance and efficiency. These include continuously variable intake and exhaust valve timing, adjustable by up to 40 degrees. This advanced valve timing system optimizes engine breathing across the RPM range, improving both power delivery and fuel economy. Another key feature is the two-stage variable length intake manifold. At lower engine speeds, a longer intake tract is employed to capitalize on the momentum of the incoming air charge, boosting low-end torque. Conversely, at higher RPMs, a shorter intake path is utilized to minimize intake friction and maximize airflow for peak power output.
So, what is it like to experience the M272 engine in action?
In terms of driving experience, the M272 engine is characterized by its eagerness to rev and its remarkably smooth power delivery. Peak torque is achieved at 5000 rpm, but a substantial portion of this torque is readily available from as low as 2500 rpm. This broad torque curve ensures responsive acceleration and ample pulling power across a wide range of driving conditions. The engine maintains its torque output at higher RPMs, allowing peak horsepower to be realized at 6000 rpm.
Below 3000 rpm, the M272 operates with a subtle and refined demeanor, with minimal induction or exhaust noise. However, as the revs climb, the engine’s sound profile transforms into a pleasing and sophisticated note, adding to the driving pleasure. When paired with Mercedes-Benz’s 7G-TRONIC automatic transmission, as often found in models like the SL, the M272 offers seamless and responsive performance. While cruising in typical traffic, it’s rarely necessary to exceed 3000 rpm, highlighting the engine’s effortless nature.
The 7G-TRONIC transmission’s ability to downshift two gears at a time ensures that brisk acceleration is always readily available. For drivers seeking even more immediate response, manual downshifts can be employed to bring the engine speed to around 4000 rpm before applying full throttle. This approach, while perhaps gentler on the transmission’s clutches and brake bands, unleashes the M272’s full potential. Even when pushed hard, the engine never sounds strained or harsh, pulling strongly all the way to and beyond 6000 rpm. For what is often considered the entry-level engine in models like the SL, the M272 consistently delivers a surprising level of performance and “shove.”
Over time, the M272 engine has garnered considerable appreciation for its well-rounded character. It possesses a distinct personality that sets it apart from some other engines in its class, even those boasting higher horsepower figures. In comparison to certain Audi engines, such as the 360-bhp V8 in the S8, and even the 2.7-liter biturbo in the RS4, which some may find tiring or aurally unpleasant, the M272 offers a more refined and engaging driving experience. Many owners report excellent reliability, with minimal oil consumption when using quality synthetic oil like Mobil 1 0W-40. Fuel economy is also respectable for its class, with figures ranging from 25-30 mpg in mixed driving conditions and potentially reaching 35 mpg on gentle highway journeys, although this can vary depending on the vehicle’s weight and driving style.
In conclusion, the Mercedes-Benz M272 engine is a truly commendable powerplant. It strikes an excellent balance between performance, refinement, and efficiency, making it a highly satisfying choice for a wide range of Mercedes-Benz vehicles. Its sophisticated engineering, smooth power delivery, and pleasing engine note have solidified its place as a well-regarded and enjoyable engine within the Mercedes-Benz lineup.
