2018 Mercedes-Benz A-Class Reliability Report

Unintended acceleration at parking-lot speeds drives most of these reports. Drivers describe the car surging forward from a stop, or after releasing the brake with the hold feature on, and the brakes not stopping it before it hits a wall. Three of the four complaints involve crashes, and one driver was taken to a hospital. A separate complaint says the cruise control set speed cannot be cleared without stopping and shutting off the engine, so re-engaging it jumps back to the old speed. Another blames poor snow grip on the sport tires.

A sudden fire is the most serious report here: dash lights came on, the steering went stiff, the car coasted to a stop, and flames spread from the engine bay through most of the car. Another driver describes a flood of alerts followed by the parking brake engaging on its own, stopping the car in traffic. Owners also complain that built-in emergency call and crash notification no longer work after backend support ended, and that a moldy cabin smell remains unfixed.

The car swerves or zigzags on its own, on the highway or while pulling out of a parking lot, with no warning light. Dealers often inspect the car and find nothing wrong. In the most serious report, the electric power steering cut out while moving and the car hit a concrete wall. The repair order cites a shorted steering rack and no communication with the steering control unit, yet warranty repair was refused. One loss-of-control report came at about 8,000 miles.

The car stalls while driving, sometimes at highway speed, or fails to start. Owners trace it to water collecting in the spare tire well and reaching the fuel pump control unit or its connector, with rust forming in the wheel well. Replacing seals and the control unit does not always stop the stalling. Several reports center on dealer repairs that did not hold and replacement parts that were not yet available, leaving cars waiting.

Early wear and sudden failure dominate these reports. Tread runs critically low at about 20,000 miles, one blowout at 35 mph led a mechanic to find all four tires in bad condition, and another tire kept losing pressure until a bubble formed in the sidewall. Dealers generally suggest replacing worn tires out of pocket. None of these reports involve a crash.

Low beams light the road poorly, and owners say night driving is difficult or that they must switch to high beams to see pedestrians and unlit streets. No warning appears because nothing has failed outright. Dealer adjustments to the headlights do not solve it, and the manufacturer says the lights perform as designed, so owners are left without a repair.

No air bag deployed in one crash that sent an occupant to the hospital. A second complaint describes the airbag warning light and a front-left malfunction message at about 46,000 miles, with a mechanic warning that the driver's air bag might not deploy. That repair was not completed. With only two complaints, no broad pattern shows, but both raise doubts about whether the air bags will work when needed.