2020 vs 2021 BMW M4
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
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Rod bearing wear All years One source so far
What to check: Ask whether the rod bearings have been replaced, and when.
Euro Premium Parts calls it the S55's most serious known issue, usually between 60,000 and 100,000 miles and sooner on hard-driven cars, and says many owners replace the bearings at around 50,000 miles.
A seller's guide (unofficial)
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Cracked turbo oil feed lines All years One source so far
What to check: Look for oil around the turbocharger housings.
Euro Premium Parts says the lines can crack or leak between 40,000 and 80,000 miles, starving the turbos of oil.
A seller's guide (unofficial)
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Cracked charge pipe All years One source so far
What to check: Listen for a hiss and feel for lost power under boost, and ask whether the plastic charge pipes were replaced with metal or silicone ones.
Euro Premium Parts says the factory plastic pipes commonly crack between 30,000 and 70,000 miles, especially on tuned cars.
A seller's guide (unofficial)
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Electric water pump and thermostat All years One source so far
What to check: Watch the temperature gauge, and ask whether the water pump has been replaced.
Euro Premium Parts says the electric water pump can fail without warning between 50,000 and 80,000 miles and overheat the engine.
A seller's guide (unofficial)
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Driveshaft recalls All years
What to check: Make sure the driveshaft recalls were done.
NHTSA lists a recall for driveshaft slip joints left without grease on some 2015 and 2016 cars, and one for the driveshaft-to-flange joint, which can fail and lose drive, on 2016 and 2017 cars including the GTS.
NHTSA
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Worn front control arm bushings All years One source so far
What to check: Listen for clunks over bumps and feel for vague steering.
Euro Premium Parts says the bushings and ball joints wear faster than expected, between 40,000 and 70,000 miles.
A seller's guide (unofficial)
2021
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Oil use on the S58 All years One source so far
What to check: Ask how often the oil has needed topping up, and check the level.
Euro Premium Parts says the S58 can use oil between services, especially when revved hard or tracked, and that more than a quart every 1,500 miles needs looking into.
A seller's guide (unofficial)
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A ticking high-pressure fuel pump All years One source so far
What to check: Listen for ticking or rattling from the fuel pump at a cold start.
Euro Premium Parts reports the noise on early cars, which BMW addressed with a software update in some markets, and a faint wastegate rattle at cold idle that is noise only.
A seller's guide (unofficial)
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Boost leaks at the charge pipe couplings All years One source so far
What to check: Feel for lost power under boost and look for a check engine light.
Euro Premium Parts says the couplings between the turbos and intercooler can leak after repeated hard use, usually between 15,000 and 40,000 miles.
A seller's guide (unofficial)
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Leaking adaptive dampers All years One source so far
What to check: Look for oil on the dampers and an uneven ride height.
Euro Premium Parts calls the adaptive M dampers a wear item that can leak between 30,000 and 60,000 miles, and costly to replace.
A seller's guide (unofficial)
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Cracked carbon-ceramic brake rotors All years One source so far
What to check: On a car with carbon-ceramic brakes, have the rotors inspected closely for cracks.
Euro Premium Parts says the rotors are sensitive to heat shock and poor bedding, and that cracks are not always visible without a close look.
A seller's guide (unofficial)
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Worn front control arm bushings All years One source so far
What to check: Listen for clunks under braking and feel for imprecise steering.
Euro Premium Parts says they wear fast on tracked or hard-driven cars, between 20,000 and 40,000 miles.
A seller's guide (unofficial)
Rare catches
2020
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Rare
M4 CS Trim
A limited run, a third of it for the US CarGurus, a published reference
1,000 built for United States, 33% of built worldwide A published reference
Good or bad: CarGurus says it has a slightly less aggressive makeover than the GTS. CarGurus
2021
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Rare
KITH Edition Package
A limited edition for the whole world Edmunds, a published reference
150 built A published reference
Recalls
2020
- 19V352000 2019–2020
The driver's and passenger's knee airbags may have been folded and fitted wrongly. Dealers replace them. NHTSA
- 20V666000 2020
Fuel injectors may have been fitted without a damping part, so vibration can damage the joint between the fuel line and fuel rail. Dealers replace the injectors and rail if it is missing. NHTSA
2021
- 21V062000 2021
The rotor and shaft inside the integrated brake system may not have been welded properly and could separate in hard braking. Dealers replace the integrated brake system. 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
What changed between
After 2020, up to and including 2021.
What it came with
2020
2021
Both years
What owners and buyers say
Reputation: what owners and the press report
2020
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Sought after: A car with the Competition Package 2017–2020 One source so far
Euro Premium Parts calls the Competition Package version the most desirable for most buyers, with more power and better suspension tuning at no great cost in reliability. A seller's guide (unofficial)
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Watch for: A car past 70,000 miles without records of the big jobs All years Less sought after One source so far
Euro Premium Parts advises avoiding cars over 70,000 miles that cannot show recent rod bearing, water pump or charge pipe work, and being wary of track use, hard tuning or irregular oil changes at any mileage. A seller's guide (unofficial)
2021
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Sought after: The M4 Competition All years One source so far
Euro Premium Parts says the Competition strikes the best balance of performance and daily use, and that the manual base car is a big draw for enthusiasts. A seller's guide (unofficial)
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Watch for: A car with hidden track use or missed oil changes All years Walk away One source so far
Euro Premium Parts advises avoiding any car with undisclosed track history, signs of deferred oil changes or an amateur engine tune, and says early 2021 cars may still carry software faults. A seller's guide (unofficial)