2020 vs 2021 BMW 4 Series

vs

Each year's own entries sit side by side, then what both share. Warnings of different generations are listed apart even under the same name, because what to check can differ.

Watch out for

Reputation: what owners and the press report. Tap one to see what to check.

2020

  • Water trapped in the convertible's rear side panels All years

    What to check: Listen for water sloshing in the rear side panels while driving, run each rear window and the roof, and look for water or a musty smell in the corners of the trunk. Ask whether the drains have been cleared.

    BMW of North America's bulletin says the rocker trim and underbody panel can sit too tight against the drain plugs, so water fills the lower rear side panels and can corrode the rear window regulators and motors, then reach the trunk's audio amplifier. It extends coverage of the drain repair to 15 years or 150,000 miles from first delivery. On a British owners' forum, owners of four convertibles in three threads report a rear window or the roof stopping working from water in the panel, and another found water running out of a sill after a car wash.

    BMW, owners' reports (unofficial)

  • Coolant leaks on the B48 four 2017–2020 One source so far

    What to check: Look for coolant at the upper radiator hose and the oil filter housing.

    Euro Premium Parts reports occasional leaks at these two points.

    A seller's guide (unofficial)

2021

  • Thermostat and coolant pump on the 430i All years One source so far

    What to check: Watch the temperature gauge on a long drive for overheating warnings or a wandering needle, and ask whether the thermostat or auxiliary coolant pump has been replaced.

    Euro Premium Parts calls the electronic thermostat and auxiliary coolant pump weak points, usually failing between 40,000 and 70,000 miles, and lists oil use and the odd high-pressure fuel pump failure on the same engine.

    A seller's guide (unofficial)

  • Oil filter housing seep on the M440i All years One source so far

    What to check: Look for oil around the oil filter housing.

    Euro Premium Parts says its gasket is prone to seeping at around 60,000 to 90,000 miles, a cheap part that takes labor to reach.

    A seller's guide (unofficial)

  • Electric water pump on the M440i All years One source so far

    What to check: Ask whether the electric water pump has been replaced on a car near 80,000 miles, and look for a coolant warning.

    Euro Premium Parts says the B58's electric water pump has a known failure pattern and advises replacing it before 80,000 to 100,000 miles.

    A seller's guide (unofficial)

  • The mild hybrid's starter-generator All years

    What to check: Ask for proof that every starter-generator and starter recall has been done, and scan for stored fault codes.

    Euro Premium Parts reports fault codes and failures of the belt starter-generator and its wiring on early cars. NHTSA lists recalls for its battery connection on 2021 M440i xDrive coupes and 2025 430i cars.

    NHTSA, a seller's guide (unofficial)

  • Worn front control arm bushings All years One source so far

    What to check: On the test drive, feel for the car following ruts in the road or vague steering.

    Euro Premium Parts says the front lower control arm bushings wear between 40,000 and 60,000 miles, especially on xDrive cars.

    A seller's guide (unofficial)

  • Early iDrive 7 glitches All years One source so far

    What to check: Try the screen, Bluetooth, reversing camera and parking sensors, and ask whether the software is up to date.

    Euro Premium Parts says early cars' screens could freeze or drop Bluetooth, mostly cured by over-the-air updates, and reports camera and parking sensor faults from damp.

    A seller's guide (unofficial)

Recalls

2020

  • 19V352000 2019–2020

    The driver's and passenger's knee airbags may have been folded and fitted wrongly. Dealers replace them. NHTSA

2021

  • 20V761000 2021

    The connection between the 48-volt battery and the starter-generator may have been assembled badly, raising its electrical resistance. Dealers inspect it and replace it if needed. NHTSA

  • 21V096000 2021

    Part of the reversing camera's picture may be blocked, or the screen may stay dark, when reverse is selected. Dealers update the camera software. NHTSA

  • 21V176000 2021

    In some side crashes the head and thorax airbag may not deploy as intended. Dealers update the software. NHTSA

  • 21V554000 2021

    The passenger seat belt's automatic locking retractor can switch off before the belt has fully retracted. Dealers inspect the retractors and replace them if needed. NHTSA

  • 23V584000 2021–2022

    The audio module's software may fail to sound the seat belt warning. Dealers update it. NHTSA

  • 25V636000 2021–2022

    The engine starter's relay can corrode, overheat and short circuit. Owners are told to park outside and away from buildings until a dealer replaces the starter. NHTSA

  • 26V056000 2021–2024

    Wear inside the engine starter can make it overheat and catch fire. Dealers replace the starter. NHTSA

What changed between

After 2020, up to and including 2021.

  1. 2021G22 begins.
  2. 2021The new 4 Series coupe and soft-top convertible arrive as the 430i and the all-wheel-drive M440i xDrive, with ventilated seats a new option. Edmunds, CarGurus

What it came with

2020

Engines
3.0L turbo inline-six (2017–2020) Edmunds, a published reference
Transmissions
Six-speed manual Edmunds, CarGurus
Body styles
Gran Coupe (2015–2020) Edmunds, a published reference
Packages
Luxury Line, later Luxury Package Edmunds, a published reference, M Sport Edmunds, a published reference, Technology Package Edmunds, Lighting Package Edmunds, Cold Weather Package Edmunds, Driver Assistance Package Edmunds, Driver Assistance Plus Package Edmunds

2021

Engines
3.0L turbo inline-six with a 48-volt mild hybrid Edmunds, a published reference
Packages
M Sport Package CarGurus, Edmunds, Dynamic Handling Package Edmunds, Parking Assistance Package Edmunds, Driving Assistance Package Edmunds, Driving Assistance Professional Package Edmunds, CarGurus, Shadowline Package Edmunds, Cooling and High Performance Tire Package CarGurus

Both years

Engines
2.0L turbo four-cylinder Edmunds, a published reference
Transmissions
Eight-speed automatic Edmunds, a published reference
Drivetrains
Rear-wheel drive Edmunds, a published reference, xDrive all-wheel drive Edmunds, a published reference
Body styles
Coupe Edmunds, a published reference, Convertible Edmunds, a published reference
Packages
Premium Package Edmunds, Convenience Package Edmunds, Executive Package Edmunds, CarGurus

Colors

2020

Nothing that 2021 lacks.

2021

  • Sanremo Green Metallic 2021 Edmunds
  • Black Sapphire Metallic 2021–2025 Edmunds
  • Portimao Blue Metallic 2021–2025 Edmunds
  • Jet Black 2021–2025 Edmunds
  • Mineral White Metallic 2021–2025 Edmunds
  • Alpine White 2021–2025 Edmunds
  • Arctic Race Blue Metallic 2021–2025 Edmunds
  • Sunset Orange Metallic 2021 Edmunds
  • Bluestone Metallic 2021 Edmunds

Interiors

2020

Nothing that 2021 lacks.

2021

  • Black Vernasca with Blue Stitching 2021–2025 Edmunds
  • Mocha Vernasca 2021–2025 Edmunds
  • Tacora Red Vernasca 2021 Edmunds
  • Canberra Beige SensaTec 2021–2025 Edmunds
  • Oyster Vernasca 2021–2025 Edmunds
  • Black Vernasca with Oyster Stitching 2021 Edmunds
  • Cognac Vernasca 2021 Edmunds
  • Black SensaTec 2021–2025 Edmunds
  • Canberra Beige and Black Vernasca 2021 Edmunds

What owners and buyers say

Reputation: what owners and the press report

2020

  • Sought after: The six-cylinder 440i 2017–2020 One source so far

    Euro Premium Parts calls the B58 six the most reliable petrol choice in this generation and highly recommends it. A seller's guide (unofficial)

2021

  • Sought after: The six-cylinder M440i All years One source so far

    Euro Premium Parts calls the M440i the sweet spot for most buyers, with near-M performance from a six it rates for long life. A seller's guide (unofficial)