M-Class Rated As "Best Pick" in SUV Crash Test

The Mercedes-Benz M-Class has been rated a "Best Pick" among popular sport utility vehicles in a rigorous series of high-speed crash tests conducted by the Insurance Institute for Highway Safety. Among the 15 SUVs subjected to a 40 mile-per-hour offset crash, none scored higher than the M-Class.

Test scoring used three major criteria: intrusion into the occupant compartment, injury measurements on a Hybrid III dummy in the driver's seat, and analysis of slow-motion film to assess how well the vehicle restraints limited dummy movement.

All passenger vehicles sold in the U.S. must pass a 30-mph crash into a wall, and since 1978, the federal government has been conducting similar "flat-barrier" crash tests at 35 mph to compare vehicle safety performance. The frontal "offset" crash represents the majority of serious real-world frontal collisions.

Not only do crash forces increase dramatically when collision speed increases another five miles per hour, but also less than half of the vehicle width collides with the barrier in an offset test. Offset crashes increase the chance of intrusion into the occupant safety cell, and can indicate how a vehicle will perform in a worst-case accident scenario.

While the Mercedes-Benz M-Class protects its occupants extraordinarily well, the M-Class is also built to be friendlier to the other vehicle as well. Designed to be compatible with passenger cars in collisions, the Mercedes M-Class features a clean-sheet design, which allowed its developers to take a fresh approach to occupant safety as well as compatibility with other vehicles.

Mercedes-Benz engineers have given considerable thought to what happens when a small car collides with a larger vehicle. While people in the smaller vehicle are usually at greater risk, thoughtful engineering can help protect the occupants of both vehicles.

Frame Structures Should Meet Squarely

Auto safety experts maintain that two key factors determine crash compatibility, especially between vehicles of disparate size. First and foremost, the main structures of the two colliding vehicles must align and meet squarely, which means that the frame members of both vehicles must be about the same height above the road. This not only reduces the possibility of one vehicle overriding the other catastrophically, but also helps the protective crumple zones designed into both vehicles to serve their purpose in absorbing crash energy.

To address this point, the frame rails of the Mercedes-Benz M-Class are about 19.5 inches above the ground, within an inch in height of the typical passenger car. In most other sport utility vehicles, this dimension (measured from the mid-point of the longitudinal frame rails to the ground) varies from about 21 inches to as high as 28 inches. However, the M-Class still has 8.5 inches of ground clearance for good off-road performance.

Crumple Zones Can Be Fine -Tuned

Secondly, the crumple zone of a larger vehicle should be somewhat "softer" than a small car, since a larger vehicle can safely absorb more crash energy and thus help protect the occupants of both vehicles. Mercedes-Benz designers have been fine-tuning crumple zone stiffness relative to vehicle size for years, and this sophisticated concept is likely to be adopted by other automakers.

Extra Crumple Zones

Although the M-Class sport utility uses a body-on-frame design, the dynamics of its crash protection are roughly equal to the Mercedes-Benz E-Class luxury sedan, which has a unibody structure. In addition to a conventional front crumple zone built into the nose of the vehicle, the M-Class incorporates a special structure around the windshield pillars. In a severe collision, this extra crumple zone can actually help dissipate some of the crash energy around the sides of the vehicle, providing even more protection for the occupants of both vehicles.