Mercedes-Benz Incident Report

2.0 Analysis of Critical System Failures

2.1 Power Train and Engine Malfunctions

The power train and engine are fundamental to vehicle operation and safety. Failures in these core components can have immediate and severe consequences, including sudden loss of control, stalling in hazardous situations, and unpredictable vehicle behavior. Customer complaints highlight several recurring patterns of malfunction that compromise driver safety and vehicle reliability.

A prevalent and dangerous issue reported by customers is the sudden loss of power, often accompanied by the vehicle entering a reduced-power "limp mode." This can be particularly hazardous at highway speeds. A driver of a 2019 Mercedes-Benz A220 reported that the vehicle suddenly "went into 'limp mode.' This occurrence caused the car to not go over 9 miles per hour." A vehicle slowing to 9 MPH on a high-speed interstate creates an extreme collision risk from trailing traffic unable to react to the sudden and drastic deceleration. Similarly, a C43 AMG owner experienced a critical failure on a highway, stating, "THE CAR ENTERS LIMP MODE IN THE HIGHWAY WHERE IT LOOSES ALL THE POWER." In a stark example of unpredictable vehicle behavior, a driver of a 380 SL reported that “the vehicle accelerated independently and crashed into a traffic sign, a parked vehicle, and a water main.”

Another critical failure pattern involves the transmission unexpectedly disengaging and shifting into neutral while the vehicle is in motion. This results in an immediate loss of motive power, leaving the driver unable to accelerate. One report for a C43 AMG describes how the "car fell out of gear into neutral and would not go back into gear unless I restarted the car." This issue is not isolated to a single model, as a similar incident was reported for an AMG GLC63 S, where the "Car will slip from drive to neutral while driving and when stopped."

The C300 model exhibits a high volume of complaints related to its fuel and propulsion system, designated with a "High" widespread level. Analysis of customer narratives reveals several distinct failure modes:

• Fuel Odors: Persistent fuel smells originating from rubber fuel components.
• Catastrophic Engine Damage: Reports of damaged spark plugs resulting from piston damage, in some cases requiring a complete engine replacement.
• Crankcase Ventilation Failure: A frequently cited issue is the failure of the crankcase ventilation valve, leading to check engine warnings and potential stalling.

These propulsion-related failures are deeply concerning, but reports indicate that vehicle control is also compromised by significant issues within steering and suspension systems.

2.2 Steering and Suspension System Concerns

Steering and suspension systems are fundamental to vehicle safety, providing the driver with essential control and maintaining stability. This section examines reports of catastrophic failures, loss of control, and chronic defects that undermine the vehicle's structural and operational integrity.

The severity of reported steering issues is underscored by a complaint from a 450SL owner who was informed by a dealer of a "cracked subframe" that could lead to a potential "'CATASTROPHIC FAILURE' of the steering system." This highlights a risk of complete and sudden loss of vehicle control due to structural failure.

Beyond structural defects, direct steering malfunctions have also been reported. The Metris model, which shows a "Medium" widespread level for steering issues, has complaints describing a "LOSS OF POWER STEERING WHEN DRIVING." A more violent incident was reported by an AMG E53 driver, who stated the "steering wheeled jerk to the right and slammed me into the side of a semi truck," resulting in a severe collision.

A particularly concerning pattern is the premature corrosion and failure of the rear subframe, which appears across multiple models. This defect can severely compromise vehicle stability and control.

Model Customer Complaint Summary

C300 Multiple reports of rusted rear subframes, with one dealer informing a customer the vehicle was "unsafe to drive because the subframe has rusted so severely."

E350 Reports of severely rusted subframes causing vehicles to fail state inspections and veer uncontrollably when braking.

These foundational mechanical systems are not the only source of concern; modern electronic braking systems also present a significant category of customer complaints.

2.3 Braking System Anomalies

This section focuses on reported failures in both conventional and advanced electronic braking systems. The reliability of a vehicle's braking system is paramount, serving as the primary active safety feature. The data reveals anomalies ranging from spontaneous, unintended engagement to complete failure to stop.

Multiple customers have reported alarming incidents of spontaneous and unintended brake engagement at speed, creating a significant risk of a rear-end collision. An owner of an AMG E43 stated, "UNEXPECTEDLY THE BRAKES ON MY E43 LOCKED UP LAUNCHING MYSELF AND MY PASSENGER FORWARD." A similar event was described by an EQS 450 driver, whose vehicle "suddenly the brakes were applied and seat belts engaged with no apparent reason or obstacle."

Conversely, reports also detail instances of complete brake failure. A complaint regarding a 2021 Mercedes-Benz AMG GLB35 involved a collision where the driver stated, "the brake pedal was depressed; however, the vehicle failed to stop as intended." Such failures represent a total loss of one of the vehicle's most critical safety functions.

Furthermore, issues have been noted with advanced brake-assist systems becoming inoperative. Multiple reports for the AMG E63 describe dashboard warnings stating "BRAKE-ASSIST INOPERABLE," indicating that a key safety feature was unavailable to the driver. The prevalence of these electronic brake faults, from phantom engagement to system inoperability, highlights a broader pattern of instability within the vehicle's core electrical and software architecture.

2.4 Electrical and Advanced Driver-Assistance System (ADAS) Malfunctions

Modern vehicles rely heavily on complex electrical architecture and software-based systems to control everything from basic functions to advanced safety features. This section analyzes a range of reported failures, from critical system shutdowns to malfunctions in driver-assist technologies that can distract drivers and create unsafe conditions.

A recurring issue that poses a direct safety risk is the failure of the instrument cluster or central display screens while driving. A CLA 250 owner described this as dangerous, noting, "Vehicle cluster lights go black while driving. dangerous due to no fuel gauge." An E300 driver reported a similar event, stating, "The entire driver instrument panel screen went blank... This is EXTREMELY dangerous," as it deprives the driver of essential information like vehicle speed.

Among the most frequently reported ADAS failures is "phantom braking," where the forward collision avoidance system engages the brakes forcefully and without reason. This pattern appears across multiple models, suggesting a potential systemic issue with the technology's calibration or sensor interpretation.

• EQS 580: "I was traveling at about 45 miles per hours on a road with no obstacles... when the car braked with no warning."
• EQB300: "We were driving along a 4 lane state road and the car suddenly applied the brakes hard and swerved to the right."
• AMG E53: "...the car CAME TO A COMPLETE EMERGENCY STOP. A RED TRIANGLE APPEARED ON THE DASH..."

Other driver-assist systems have also been reported to behave erratically. An owner of an AMG GLC43 described an incident where the lane-keeping assist function would "VIOLENTLY MOVE THE VEHICLE UNASSISTED BY DRIVER ONTO ACCESS ROADS." Beyond these advanced electronic systems, patterns of physical structural failures have also been reported by customers.

2.5 Structural Integrity Issues

This section addresses customer complaints related to the vehicle's structural components, including glass panels and body elements. These issues represent significant concerns regarding build quality and safety, as failures can occur unexpectedly at high speeds, posing a risk to occupants and other motorists.

A significant number of complaints describe panoramic sunroofs spontaneously shattering or "exploding" while the vehicle is in motion. This phenomenon is reported across a diverse range of models, including sedans and SUVs, indicating a potential widespread material or design flaw.

Model Customer Complaint Summary

AMG GLC43 "Panoramic Sunroof exploded while driving out of the blue. No other cars in front of me or near me."

C43 AMG "I was driving on the highway, with no other cars near me and my panoramic sunroof exploded. It made a very loud gunshot like sound and I felt shards of glass fall on my head while driving."

E350 "I WAS DRIVING MY MERCEDES E350 ON THE HIGHWAY AT 60 MPH WHEN I HEARD AN EXPLOSION. THE SUNROOF HAD EXPLODED..."

GLB250 "...while driving 65 - 70 mph, a loud noise was heard, and the sunroof glass exploded."

In addition to glass failures, reports also point to issues with structural bonding. Multiple complaints regarding the C300 model describe incidents where the rear windshield detached from the vehicle because it was "not properly bonded." This failure not only compromises the vehicle's structural integrity but also poses a direct threat to other motorists, as a detached windshield can become a large, high-velocity projectile on the roadway. The various system failures identified in this analysis reveal several overarching themes.

3.0 Summary of Key Thematic Findings

This final section synthesizes the detailed incidents from the preceding analysis into high-level themes. These themes suggest that the reported problems are not merely isolated events but may point to potential systemic issues in design, manufacturing, or quality control.

1. Recurrence of Critical Control Failures Across Models: Core safety systems exhibit similar failure modes across a diverse range of Mercedes-Benz models and classes. The consistent reports of sudden power loss (limp mode), unexpected transmission disengagement into neutral, and erratic acceleration or deceleration point to potential systemic vulnerabilities in power train and vehicle control architecture that are not confined to a single platform.

2. Unreliability of Advanced Electronic Safety Systems (ADAS): A clear trend of failures exists within software-dependent safety features. Most notably, "phantom braking"—where the automatic emergency braking system engages without any actual hazard—and erratic lane-keeping assist actions are frequently reported. These malfunctions suggest a pattern of unreliability where the safety systems themselves can create hazardous driving conditions by causing unexpected and dangerous vehicle behavior.

3. Pattern of Structural and Material Integrity Deficiencies: The widespread reports of exploding sunroofs, detached window glass, and prematurely corroded subframes across multiple vehicle classes strongly indicate systemic deficiencies in material selection, manufacturing process control, or long-term environmental durability validation. The cross-model recurrence of these distinct structural failures suggests the root cause may lie in shared components or production standards rather than model-specific defects.

4.0 Conclusion

In summary, this analysis of customer complaints reveals significant and recurring patterns of safety-critical failures in power train, steering, braking, electronic, and structural systems across numerous Mercedes-Benz models. The consistency of these reported issues—from sudden power loss and phantom braking to corroding subframes and shattering sunroofs—suggests that these problems may be systemic in nature. The findings presented in this report indicate that these areas warrant further investigation to determine the root causes and assess the full scope of potential safety risks.