Home · 2021 Mercedes-benz S-class Phev · Complaints

What 33 owners told NHTSA about the 2021 Mercedes-benz S-class Phev

These are the actual owner complaints behind this car’s reliability verdict, filed with the federal government, unedited. They’re unverified reports, not confirmed defects: read them as leads for your pre-purchase inspection, not a diagnosis.

All (33)Crash / fire / injury (4)Electrical system (10)Wheels (6)Driver assistance (5)Engine & cooling (5)Brakes (3)Engine (3)Lane Departure (3)Speed control (3)Communication (2)Fuel system (2)

Newest first · 33 complaints · page 2 of 2

Jan 27, 2022Electrical systemSpeed controlEngine

Background: This is a V-8, gas vehicle.The 12-volt battery gives CRITICAL CHARGE notifications constantly. Incident: Dry pavement, 400-mile, January winter night, highway driving in Wisconsin Northwoods at posted 70 mph; some with cruise control, some without cruise control. Seat belt was in use. On four occasions, car independently, without any warning, dropped from 70 mph to 35 mph, projecting me forward. No reduction in speed signage No small town drive through. With car and semi-truck traffic behind me, luckily no rear end collisions, injury or death occurred. During dealership repair service 12/09/2021 - 12/17/2021, along with mailed pending recall from manufacturer for ENGINE CONTROL SOFTWARE UPDATE, was told December 28, 2021 it would occur. When car returned for service on 01/18/2022 (and is still in for service today - 01/26/2022), I was told 01/14/2022 was the update release. I have not received any updated manufacturer notifications. Dealership (Illinois) says CONTROL MODULE on order from West Coast. (Photo - Portion of text response from Dealership Service Writer on 01/26/2022 is attached.) Dangerous vehicle. This newly designed model has engineering problems. Should not have been released to sales market. Numerous ELECTRICAL Problems have occurred since my August 5, 2021 purchase.

NHTSA ODI 11449057

Jan 5, 2022Engine & coolingElectrical system

The contact owns a 2021 Mercedes-Benz S580. The contact stated that while driving, the navigation system became inoperable. There were several unknown warning lights illuminated. The contact received notification of NHTSA Campaign Number: 21V843000 (Engine and Engine Cooling) however, the part to do the recall was unavailable. The vehicle was taken to the local dealer however, the mechanic was unable to duplicate the failure. The contact stated that the manufacturer exceeded a reasonable amount of time for the recall repair. The manufacturer was notified of the failure however, no further assistance was provided. VIN tool confirms parts are not available. The approximate failure mileage was 600.

NHTSA ODI 11446332

Dec 16, 2021BrakesDriver assistanceCrash

The contact owns a 2021 Mercedes-Benz S580. The contact stated while driving approximately 5 MPH, the brakes failed to function as needed while the brake pedal was being depressed. The failure resulted in a crash. There were no injuries sustained. The contact stated that the accident occurred due to the failure in the braking system as well as the intelligent driving feature. The contact stated that the vehicle inadvertently shutoff and restarted without driving input. The brake assist feature did not engage because the driver was already actively depressing the brake pedal. The contact stated no warning light was illuminated. The vehicle was taken to a local dealer where it was test-driven for two miles however, the contact was yet to receive any information on a possible cause for the failure. The contact was concerned that it was only a matter of time before an even more serious accident would occur. A police report was not filed. The manufacturer was contacted, and the contact requested to be provided the diagnostic report, the Event Data Recorder (EDR) info, and the front camera info. The contact was informed that if she provided any videos or subsequent pictures prior to the crash, she would be provided the information that she requested. The contact later received a letter stating that she would not be provided the information requested. The contact was provided with no further assistance. The vehicle was not repaired. The failure mileage was approximately 1,194.

NHTSA ODI 11444036

Dec 13, 2021Engine & cooling

The contact owns a 2021 Mercedes-Benz S580. The contact received a notification for NHTSA Campaign Number: 21V843000 (Engine and Engine Cooling) however, the part to do the recall repair was unavailable. The dealer had been notified about the recall; however, the contact was informed that the parts were not yet available. The manufacturer had also been notified of the recall but offered no assistance. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The contact had not experienced a failure. VIN tool confirms parts not available.

NHTSA ODI 11443625

Nov 29, 2021Speed controlTransmission & drivetrainCrash1 injury

The contact owns a 2021 Mercedes-Benz S580. The contact stated while driving at 60 MPH, the contact pressed a button on the steering wheel to engage the cruise control function on the vehicle. The contact stated when driving past a mileage sign stating 40 MPH, the vehicle suddenly reduce in speed to 40 MPH, while the contact was on the highway in the fast lane. The contact was able to move the vehicle over to the side of the road waited a few minutes took off the cruise control function and reapplied it back on and continued to drive the vehicle again. After a few minutes when the contact was exiting off the highway and the contact drove past a sign that said 60 MPH when suddenly the vehicle automatically accelerated on its own which caused the contact to rear-end a parked vehicle in front of them. The air bags did not deploy or the S.O.S. signal did not turn on. The contact was injured where they broke two bones in the right foot, left knee injury, and whiplash on their neck due to the seat belt. There was medical treatment at the scene. A police report was filed. The vehicle was towed to a local dealer where the vehicle was inspected but could not diagnose the caused the failure. The vehicle was not repaired. The manufacturer was made of the failure. The failure mileage was approximately 976.

NHTSA ODI 11442018

Nov 11, 2021Electrical system

Upon startup, the back up camera will not display when putting the car in reverse. I could not see if any pedestrians were behind me when backing out of a parking spot. This problem has happened 2 times in the last 2 weeks. So far, the camera resumes working after the car has been turned off and restarted. I called the Mercedes dealership service center and they suggested I make a service appointment to repair the camera system. The car is 3 months old. I will make an appointment to have the car serviced soon.

NHTSA ODI 11440126

Sep 2, 2021Visibility & wipers

2021 MERCEDES BENZ S580. CONSUMER WRITES IN REGARDS TO OBSTRUCTED VIEW THRU FRONT WINDSHIELD. THE CONSUMER STATED THE DASHBOARD REFLECTS ONTO THE WINDSHEILD. THE DEALER AND MANUFACTURER WERE NOTIFIED, BUT DID NOT OFFER ANY ASSISTANCE.

NHTSA ODI 11431500

Jul 26, 2021Speed controlLane Departure1 injury1 death

UNKNOWN

NHTSA ODI 11426542

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Working with the data? Download all 33 complaints as CSV · fetched from NHTSA July 20, 2026

How to use these: a complaint is one owner’s report, filed voluntarily and published unverified. Patterns matter more than any single story. If several owners describe the same failure at similar mileage, put that system at the top of your pre-purchase inspection list. Back to the full 2021 Mercedes-benz S-class Phev verdict →