The Lemon Index
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BMW's 3.0 L twin-turbo inline-6 in the 2 Series, 4 Series, M3, model years 2015–2021. YouTube likes the 2020 best.
Middle of the pack: YouTube owner tone 50/100, #77 of 165 engines with a YouTube study (in the middle third); no engine-related recall on record, 5 known issues listed below.
Reliability by year
YouTube videos are most positive about the 2020 (55) and least about the 2016 (47); neighboring years share many of the same videos, so small gaps mean little.
Owner score = the whole car's Lemon Index where this was its only engine that year; a gray dot means the model shared engines, so the number isn't this engine's alone. How we count
How each number is matched to the engine: (a) complaints filed under a version name that used only this engine that year (e.g. "335I"); (b) the model had only this engine that year, so its Lemon Index (complaints per car sold vs the average car) applies to every car with this engine; "all engines combined" = the model had several engines under one name, so its number is not this engine's alone. Owner complaints cover the whole car (brakes, air bags, electrics ...), not only the engine. None of these is a failure rate. YouTube tone = how positive the videos are, 0–100, from titles and transcripts that name the engine or a version that used it. A video whose title names no model year counts toward every year of its generation, so neighboring years share most of their videos.
All the numbers, year by year
| Year | Cars with it | Owner complaints | Complaints naming "S55" | YouTube says | Top complaint areas |
|---|---|---|---|---|---|
| 2015 | BMW M3 M3 BMW 4 Series M4 | 4 complaints (b: only engine in BMW M3; no sales data, so no per-car score) | 2 | 49 (112 videos, 3 naming 2015) | fuel system, engine, other |
| 2016 | BMW M3 M3 BMW 4 Series M4, M4 GTS | 5 complaints (b: only engine in BMW M3; no sales data, so no per-car score) | 2 | 47 (113 videos, 4 naming 2016) | engine, other, body & structure |
| 2017 | BMW M3 M3 BMW 4 Series M4 | 3 complaints (b: only engine in BMW M3; no sales data, so no per-car score) | 0 | 49 (112 videos, 3 naming 2017) | electrical, transmission & drivetrain, fuel system |
| 2018 | BMW M3 M3, M3 CS BMW 4 Series M4, M4 DTM Champions Edition | 9 complaints (b: only engine in BMW M3; no sales data, so no per-car score) | 0 | 50 (115 videos, 6 naming 2018) | fuel system, other, engine |
| 2019 | BMW 4 Series M4, M4 CS, M4 Competition BMW 2 Series M2 Competition | all engines combined: BMW 4 Series 26 complaints; BMW 2 Series 1 complaints | 0 | 51 (100 videos, 10 naming 2019) | — |
| 2020 | BMW 4 Series M4, M4 CS, M4 Competition BMW 2 Series M2 CS, M2 Competition | all engines combined: BMW 4 Series 6 complaints; BMW 2 Series 7 complaints | 0 | 55 (110 videos, 7 naming 2020) | — |
| 2021 | BMW 2 Series M2 Competition | all engines combined: BMW 2 Series 10 complaints | 0 | 48 (71 videos, 5 naming 2021) | — |
Known issues on record
- Crank hub (Owner-reported, disputed). The crank hub is pressed on, not keyed. Under high torque, mostly on tuned cars, it can slip and knock the timing out. BMWBLOG calls it rare but serious. Fix: Aftermarket keyed or pinned hub. 13 owner complaints to NHTSA mention it (F80 M3, F82 M4).
- Carbon on intake valves (Owner-reported). Direct injection lets carbon build on the intake valves: rough idle and misfires. Fix: Walnut-blast the valves.
- Gasket oil leaks (Owner-reported). Valve cover, oil pan and oil filter housing gaskets leak with age. Fix: Replace the gaskets.
- Oil leaks (Outlet). Gaskets wear with age. BMWBLOG names the valve cover, oil pan and oil filter housing gaskets as common leak points. Fix: Replace the leaking gasket.
- Carbon buildup (Outlet). Direct injection lets carbon collect on the intake valves over time, which can cause rough idle and misfires. Fix: Clean the intake valves at intervals. 1 owner complaint to NHTSA mention it (F82 M4).
Sources: BMWBLOG: BMW S55 engine overview (2023), Studio RSR: S55 crank hub fix (F80 M3 / F82 M4). The same list as on the M3 page, the M4 page.
Every US version with this engine
| Model and version | Years | Power |
|---|---|---|
| BMW M3 M3 | 2015–18 | 425 hp |
| BMW M3 M3 CS | 2018 | 453 hp |
| BMW 4 Series M4 | 2015–20 | 425 hp |
| BMW 4 Series M4 GTS | 2016 | 493 hp · 443 lb-ft |
| BMW 4 Series M4 DTM Champions Edition | 2018 | 493 hp · 443 lb-ft |
| BMW 4 Series M4 CS | 2019–20 | 453 hp |
| BMW 4 Series M4 Competition | 2019–20 | 444 hp |
| BMW 2 Series M2 Competition | 2019–21 | 405 hp · 406 lb-ft |
| BMW 2 Series M2 CS | 2020 | 444 hp |
Versions and years: EPA (fueleconomy.gov). Engine and power: Wikipedia, BMW S55 (BMW ratings; US figures can differ by a few hp).
Quick answers
What cars have the BMW S55 engine?
In the US: the 2 Series, 4 Series, M3, model years 2015–2021. See the version table for each one.
Is the S55 reliable?
Mostly, with known issues to check. YouTube owner tone 50/100, #77 of 165 engines with a YouTube study (in the middle third); no engine-related recall on record, 5 known issues listed below. The most owner complaints (about any part of the car) filed under version names that used this engine were for the 2018 (9). Counts follow sales, so this is not a failure rate. Government complaints are filed by model and year, not engine, and they cover the whole car, so none of these numbers is an engine failure rate. We only credit a number to this engine where the version name or the model year leaves no doubt. Have any used car inspected.
How much horsepower does the S55 make?
BMW rated it at 405 to 493 hp in US versions, depending on the car and year.