BMW 420i
Modular four-cylinder turbo, the workhorse of the current model range. Very broad power spectrum from 135 to 306 hp. Reliable; watch oil consumption and turbocharger at high mileage.
Modern Coupe
Rear-wheel drive, reliable, modern design.
Engine Weaknesses 6
Timing chain guide rail can break; chain jump and engine damage follows. More common on early production years and with spirited driving.
Symptoms: Rattling, clattering from the engine, sudden power loss, engine damage
Oil filter housing with integrated oil/water heat exchanger leaks. Coolant loss and overheating risk from about 60,000 km.
Symptoms: Coolant level warning, oil puddle under engine, overheating
A plastic bleed line between the cylinder head and expansion tank becomes porous and breaks. Coolant loss follows; the mounting location is difficult to access, so labour costs dominate.
Symptoms: Dropping coolant level; coolant warning on the instrument cluster; faint sweet smell; no visible puddle under the car
The wastegate linkage on the B48 turbocharger has too much play by design and rattles, especially on cold start and at low revs. BMW offers a repair kit (e-actuator 11655A7A286) as a goodwill measure.
Symptoms: Metallic rattling or clattering from the turbo area on cold start and at idle; disappears at higher revs
As a direct-injection engine the B48 does not wash the intake valves with fuel. Oil vapour from crankcase ventilation and EGR gases form deposits that reduce flow and cause misfires.
Symptoms: Stumbling on cold start; power loss at high revs; rough idle; increased fuel consumption
The crankcase ventilation (PCV) integrated into the valve cover wears out and allows oil into the intake tract. Because PCV and valve cover are a single unit on the B48, the entire cover must be replaced.
Symptoms: Increased oil consumption (>0.5 L/1,000 km); blue smoke on cold start; oil in the intake line; rough idle
Vehicle Weaknesses 14
Official recall: moisture can enter the starter motor and cause corrosion. In extreme cases there is a fire risk.
The recall for moisture-induced starter corrosion also affects the G82 M4.
On early G22/G26 models, sporadic complete software failures: iDrive freezes, navigation fails.
On the M440i xDrive with 48V mild hybrid, the battery can become deeply discharged after short-distance driving.
After extended periods of inactivity, brake discs rust so heavily that the parking brake seizes and disc replacement becomes necessary.
After software updates, unwanted downshifts at 120 km/h to 7th gear. Sporadic electrical errors after service.
Climate control fails periodically around freezing point — compressor cycles off, the anti-mist sensor re-engages it.
M Sport suspension shock absorbers can gradually wear from around 75,000 km.
Standard M compound brake discs squeal at low speeds below 50 km/h. BMW classifies this as design-inherent.
On the G82 M4 xDrive, the tyre makes contact with the bumper cover at full lock.
On the G82 M4, annoying wind noise at the driver's door appears from around 130 km/h. Cause is a door seal or door frame gap not sitting flush; dealers resolved it through readjustment.
Front control arm rubber bushings develop creaking and clicking noises at low temperatures. BMW has provided replacement parts with a Teflon coating.
Many G82 owners report unusually large and deep stone chip damage even on new cars. The paint layer is thinner than on predecessor models; chips of 3–10 mm after a short period of use are normal.
On some G82 M4s, a metallic click occurs when shifting from reverse to neutral or downshifting to a stop. BMW service has replaced the park lock mechanism in documented cases.
Reports & Tests
2 owner complaints filed with NHTSA (2020–2026). Most reported: Other (2), Brakes (2), Collision Avoidance (1).