2020 BMW 4 Series Reliability Report

Reports here cover unrelated problems. Two describe the car moving without input. In one, a car rolled forward with nobody inside and hit a garage door. In the other, the backup assistant disengaged and the car sped backward into a brick wall. A panoramic sunroof shattered while the car was being driven, and the driver was hurt. Other owners report over-the-air updates that download but never install, and a failed lower active grille that turned on the check engine light, with the repair cost refused based on VIN.

A front tie rod buckles while backing into a parking space at under 5 mph, with no impact, and two technicians find no sign of a collision. In another report, a system locks up at highway speed after a dealer repair, sending the car off an exit ramp and causing a back injury. A third complaint blames possible damage from a tow truck. These few reports share no common cause.

The serious reports describe a sudden shutdown while driving. Power steering assist cuts out and the engine switches off. In one case the car crashed and was totaled. Another owner lost all engine and electrical power in busy traffic with no warning lights. One complaint filed here is really about the open fire-risk recall, with the owner waiting months for a response and unsure whether an independent mechanic can work on the car.

Injury reports here involve trim and hardware, not crash structure. Aluminum trim on the center console peels away near the lid button, leaves a sharp edge and cuts fingers. One person was hurt reaching through the grille for the secondary hood latch. Another buyer got warning lights and side-to-side sway soon after purchase and then learned the car had earlier accident damage to a structural safety part. That points to the car's history, not its design.

Coolant loss leads to overheating. Drivers see a low coolant light with an engine overheating message, find coolant leaking under the engine, and in one case the engine stalled. A cracked expansion tank leaked onto the fuel rail, and an injector failed, at about 48,000 miles. In another case the dealer couldn't find where the coolant was leaking. Repairs range from replacing the tank and injector to a long list of hoses, seals and gaskets.

Headlight housings fog up in the rain, scatter the low beams and light only 15 to 30 feet of road. One report puts this at about 34,000 miles. Dealers say they can't confirm it because the lenses are clear by the time the car arrives. Other owners point out that the instrument cluster has no low-beam indicator, so the daytime running lights can be mistaken for headlights, and that the cluster's auto-dimming makes it hard to read in daylight.

The car fails to stop when the brake pedal is pressed, usually at low speed and often with no warning light. One case ended in a rear-end crash that injured both drivers, and the dealer found nothing wrong even though the problem came back. Another car needed a new brake booster at about 86,000 miles. In a third, the car suddenly slowed almost to a stop with several warning lights on, and a mechanic blamed the integrated braking system.