The quest to prevent car collisions began with the automobile itself, but it wasn’t until the late 1990s that technology truly accelerated to create systems capable of intelligently assisting drivers in maintaining safe distances. Adaptive Cruise Control (ACC) emerged as a groundbreaking feature, representing a significant stride towards autonomous driving. While early iterations required refinement, the introduction of Distronic in the 1999 Mercedes Benz S-Class marked a pivotal moment in this technological evolution.
Early explorations in adaptive cruise control saw manufacturers experimenting with different sensor technologies. In 1991, Mitsubishi ventured into lidar with a system in its Debonair, although it functioned merely as a warning system without speed regulation. Mitsubishi furthered this development by introducing the Preview Distance Control system in the 1995 Diamante sedan. This system, incorporating lidar and a camera, could adjust the car’s speed by easing off the accelerator or downshifting, but lacked the ability to engage the brakes. Limitations such as no braking intervention, a 67mph operational limit, and poor performance in adverse weather restricted this system primarily to the Japanese market. Toyota followed suit in 1997 with a Denso-developed lidar system on the Celsior (Lexus LS in Japan), also without braking capabilities, further highlighting the nascent stage of adaptive cruise control technology.
The 1999 Mercedes Benz S-Class Distronic system marked a significant leap forward, tailored for diverse driving conditions, including high-speed autobahns common in Europe and roads in the US. Mercedes-Benz addressed critical limitations of previous systems by incorporating two key advancements. Firstly, following the ‘elk test’ incident with the A-Class in 1997, Mercedes made Electronic Stability Program (ESP) standard across its range. This meant the 1999 S-Class already had the infrastructure for automatic braking, resolving a major shortfall of earlier Japanese systems. Secondly, Distronic employed radar technology instead of lidar. While lidar is now prominent in autonomous systems, in 1999, radar offered advantages in cost-effectiveness and superior performance in rain, fog, or dust – conditions that could hinder lidar’s effectiveness. This radar-based system in the 1999 Mercedes Benz S-Class could operate at higher speeds and, crucially, intervene with braking, offering a more robust and practical adaptive cruise control solution for a wider range of driving scenarios.
Following Mercedes-Benz’s lead with the 1999 S-Class, other manufacturers adopted radar, integrated stop-and-go functionality, and added cameras and sensors for lane-keeping assist. These progressive enhancements have transformed adaptive cruise control from a Level 1 ADAS feature to Level 2, forming the bedrock for the autonomous driving technologies we see developing today. The 1999 Mercedes Benz S-Class and its Distronic system were not just an incremental improvement, but a paradigm shift that paved the way for modern driver-assistance systems and the future of autonomous vehicles.
