2018 BMW 4-Series Reliability Score & Common Problems

Owners of the 2018 BMW 4-Series frequently report issues related to coolant and oil system leaks, often citing cracked plastic components as the cause, particularly around 60,000 to 70,000 miles. Symptoms include overheating and potential mixing of oil and coolant, which can lead to further engine damage. Several complaints also mention malfunctions in the vehicle's safety systems, such as ineffective rear cross-traffic alerts and inadequate lane departure warnings, which may compromise driving safety. Notably, there are reports of unintended acceleration and a fire incident, both of which resulted in injuries, highlighting significant safety concerns. Buyers should be aware of these recurring issues and their potential impact on vehicle reliability and safety.

Owners of the 2018 BMW 4-Series frequently report issues with the passenger restraint system and seat belts. Common symptoms include a persistent "passenger restraint system malfunction" warning and false seat belt alerts, even when the seat is unoccupied or the seat belt is fastened. Some complaints mention the need for expensive repairs, such as sensor mat replacements, typically costing around $2000 to $2800. One report involves a crash where the passenger seat belt failed to lock properly, resulting in an injury. These issues often occur at varying mileages, with at least one case noted at 77,000 miles. Potential buyers should be aware of these reported malfunctions and the associated repair costs.

Owners of the 2018 BMW 4-Series frequently report issues related to coolant leaks, with multiple complaints indicating problems with the water pump and coolant hoses. Symptoms commonly described include illuminated coolant warning lights, engine overheating, and visible coolant leaks under the vehicle. These issues often occur around 50,000 to 80,000 miles, with some reports of repeated failures after repairs. Additionally, some owners experience engine stalling and reduced power, with one instance of engine combustion and smoke entering the cabin, which could have safety implications. Buyers should be aware of these recurring cooling system problems when considering this model.

Owners of the 2018 BMW 4-Series frequently report powertrain issues, particularly involving stalling and sudden acceleration. Common symptoms include the vehicle shutting off unexpectedly while driving or at a stop, error messages such as "drivetrain malfunction," and significant rattling or shaking during cold starts. Some complaints involve serious safety implications, including two crashes with injuries, one involving unexpected acceleration and another involving loss of control at higher speeds. These issues often occur at relatively low mileages, such as 22,000 miles, and are sometimes associated with fuel pump and driveshaft flex disc failures. Buyers should be aware of these potential problems and the associated safety risks when considering this model.

Owners of the 2018 BMW 4-Series frequently report issues related to the fuel system, particularly with diesel models. Complaints often mention problems such as the vehicle shuddering or stalling while driving, failure to start, and abnormal fuel odors. These issues are sometimes linked to a recall that owners indicate has not been resolved due to unavailable parts. The failure mileage reported by owners varies, with some incidents occurring around 34,914 miles and others at higher mileages like 102,000 miles. While no crashes or fires are reported, the stalling and shuddering at highway speeds may pose safety risks.

Owners of the 2018 BMW 4-Series report issues with vehicle speed control, particularly involving the cruise control system and sudden unintended acceleration. One complaint describes a stuck cruise control rocker switch that causes the vehicle to accelerate uncontrollably, increasing speed from 61 mph to over 80 mph, posing a risk of collision. Another owner reports a crash resulting from unexpected acceleration while parking, which mirrors a similar issue experienced with a previous BMW model. These incidents typically occur at varying mileages and involve scenarios where precise speed control is crucial, such as merging or parking. Two complaints involve crashes, highlighting potential safety implications, including loss of control and collision with stationary objects.

Owners of the 2018 BMW 4-Series report issues related to unexpected acceleration and brake failure, with some incidents leading to crashes. Complaints frequently mention the vehicle accelerating while the brake is applied, occurring in both stationary and moving situations. One owner describes the brakes failing to stop the vehicle, resulting in a collision, while another notes the absence of a brake wear warning light despite severe pad wear. These issues are reported at various mileage points, including around 25,000 and 40,000 miles. The safety implications are significant, as multiple reports involve crashes or near-misses, highlighting potential risks for used car buyers.