BMW Z4 G29
Weaknesses, engine ratings and buying advice
The G29 (2018–present) is the current Z4 — co-developed with the Toyota Supra but a standalone car. Fabric soft top instead of folding hardtop (weight saving), automatic only (no manual), BMW B-engines. More roadster, less GT than the E89.
Engines: The B58B30 in the M40i (250 kW) is the heart — one of the best BMW engines, inline-six turbo with Supra genes. The B48B20 in the sDrive20i/30i (145–190 kW) is the solid four-cylinder turbo entry.
Weaknesses are growing pains of a modern car: Soft top creaks (hood weatherstrip, rubber buffers, $110–660). Panel gaps on front bumper/bonnet on early cars (2018–2020). Tail light cracks — design issue with tight gaps, BMW fitted protective film from the factory ($220–500). Differential dust caps detach on the M40i — squeaking in warm weather ($0–550, free under warranty). iDrive settings reset themselves. Suspension sensor bracket can break — limp mode.
Test-drive checklist: Soft top for noise while driving. Tail lights for cracks. M40i: squeaking at 30–60 km/h in warm weather (diff dust caps). OTA update issues: check iDrive settings after restart.
2026 market: sDrive20i from $30,800–39,600. sDrive30i $35,200–46,200. M40i $46,200–63,800.
Insider pick: M40i B58B30 (2019–2022) — 340 hp inline-six roadster, fabric soft top, 1,535 kg. The best BMW roadster since the Z4M. Strong depreciation from new makes it a used bargain.
Generations
Engine Overview
The BMW Z4 G29 is available with 4 engine variants — from 136 to 387 hp.
Modular four-cylinder turbo and workhorse of the current BMW lineup. Wide power range from 135 to 306 hp (M135i/M235i). Structurally the best four-cylinder petrol BMW has ever built: timing chain at front, closed oil circuit, Valvetronic variable valve lift. Oil consumption stays under control when BMW-spec oil (LL-01 or LL-17FE+) is used. Typical wear items are the electric water pump (from around 80,000 km) and the high-pressure pump with direct injection. Not an engine to fear — but BMW service intervals are too long; those who care for their B48 change oil every 10,000-12,000 km.
- !! Timing chain guide rail breaks from 60,000 km
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 leaking — coolant loss from 60,000 km
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 - !! Coolant bleed line at cylinder head breaks from 70,000 km
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
+ 6 more engine weaknesses + vehicle weaknesses
Closed-deck aluminium block as standard — a feature normally reserved for racing engines. Water-cooled turbo with mechanical wastegate linkage that rattles at cold start — by design, not dangerous. Barely audible at idle; from 3,000 rpm a rich, deep six-cylinder thrust builds linearly to 6,500. The B58 sounds fuller than the S55 from outside — but inside the motorsport aggression is absent. Dual injection (direct + port) reduces intake valve carbon build-up significantly. The PCV membrane in the valve cover is the known weakness: BMW had to extend the warranty to 15 years. Plastic oil filter housing cracks around 100,000 km — coolant mixes into oil, act immediately. Oil changes every 10,000 km; inspect the cooling system from 70,000 km. Tuning: Stage 2 brings 500 hp — the closed deck makes it possible.
- !! Oil filter disintegrates — engine damage risk from 30,000 km
On B58-equipped M140i/M240i the oil filter can disintegrate on first change and distribute filter material through the oil circuit. BMW covers the costs with proven service history.
Symptoms: Oil pressure warning, metallic noises, engine damage after oil change - !! Plastic oil filter housing cracks — coolant/oil mixing from 100,000 km
The plastic oil filter housing becomes brittle from heat cycling and cracks — often during oil changes from overtightening the filter cap. Coolant and oil mix; engine damage likely if unnoticed.
Symptoms: Milky oil on the filler cap, coolant loss without visible leak, oil pressure warning, coolant level drops slowly - !! PCV valve / valve cover membrane failed from 80,000 km
The PCV membrane in the integrated valve cover tears or hardens from heat cycles. Crankcase builds positive pressure, oil is forced through seals. BMW extended the warranty to 15 years/150,000 miles.
Symptoms: Whistling or squealing from the engine bay, white or blue smoke, rough idle, oil in the charge pipe or air filter
+ 9 more engine weaknesses + vehicle weaknesses
Modular four-cylinder turbo and workhorse of the current BMW lineup. Wide power range from 135 to 306 hp (M135i/M235i). Structurally the best four-cylinder petrol BMW has ever built: timing chain at front, closed oil circuit, Valvetronic variable valve lift. Oil consumption stays under control when BMW-spec oil (LL-01 or LL-17FE+) is used. Typical wear items are the electric water pump (from around 80,000 km) and the high-pressure pump with direct injection. Not an engine to fear — but BMW service intervals are too long; those who care for their B48 change oil every 10,000-12,000 km.
- !! Timing chain guide rail breaks from 60,000 km
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 leaking — coolant loss from 60,000 km
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 - !! Coolant bleed line at cylinder head breaks from 70,000 km
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
+ 6 more engine weaknesses + vehicle weaknesses
Modular four-cylinder turbo and workhorse of the current BMW lineup. Wide power range from 135 to 306 hp (M135i/M235i). Structurally the best four-cylinder petrol BMW has ever built: timing chain at front, closed oil circuit, Valvetronic variable valve lift. Oil consumption stays under control when BMW-spec oil (LL-01 or LL-17FE+) is used. Typical wear items are the electric water pump (from around 80,000 km) and the high-pressure pump with direct injection. Not an engine to fear — but BMW service intervals are too long; those who care for their B48 change oil every 10,000-12,000 km.
- !! Timing chain guide rail breaks from 60,000 km
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 leaking — coolant loss from 60,000 km
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 - !! Coolant bleed line at cylinder head breaks from 70,000 km
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
+ 6 more engine weaknesses + vehicle weaknesses
Vehicle Weaknesses
| Weakness | Cost | |
|---|---|---|
| Soft Top: Noise and Creaking from Hood Band The G29 Z4's soft top tends to creak and twist, especially at high speeds and in varying weather conditions. The hood retaining band is a known sub-optimal solution — BMW has not provided a complete fix. Symptoms: Creaking and squeaking from the roof while driving, especially in cold conditions or wind, plastic-like squealing | Low | |
| Body Panel Gaps: Front Bumper and Bonnet Early G29 models show noticeable quality issues with panel gaps on the front bumper and bonnet. The panels are not flush — a typical early production issue that was corrected during the production run. Symptoms: Visibly uneven gaps between bumper and wings, bonnet does not sit flush | Low |
Test Reports
TÜV Report 2024
The Z4 G29 shows barely any defects at MOT as a young model.
2023-11ADAC Breakdown Statistics 2024
The Z4 G29 benefits as a modern BMW model from the brand's generally strong breakdown record.
2024-04Top Reported Issues
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Explore more
Known Problems and Issues +
A total of 29 weaknesses have been documented for the BMW Z4 G29 (2019–2026) — 21 engine-related and 8 vehicle-related. Typical issues affect Body, Electronics, Gearbox, Suspension.
Z4 (B48B20, 2018–2026) — Be Careful: Timing chain guide rail breaks, Oil filter housing leaking — coolant loss, Coolant bleed line at cylinder head breaks. Power: 156–163 PS.
Z4 (B48B20, 2019–2026) — Be Careful: Timing chain guide rail breaks, Oil filter housing leaking — coolant loss, Coolant bleed line at cylinder head breaks. Power: 197 PS.
Z4 (B48B20, 2019–2026) — Be Careful: Timing chain guide rail breaks, Oil filter housing leaking — coolant loss, Coolant bleed line at cylinder head breaks. Power: 258 PS.
Z4 (B58B30, 2019–2026) — Be Careful: Oil filter disintegrates — engine damage risk, Plastic oil filter housing cracks — coolant/oil mixing, PCV valve / valve cover membrane failed. Power: 374 PS.
Z4 (B58B30, 2019–2026) — Be Careful: Oil filter disintegrates — engine damage risk, Plastic oil filter housing cracks — coolant/oil mixing, PCV valve / valve cover membrane failed. Power: 387 PS.
What to watch out for with the BMW Z4? See the detailed listing of all engine and vehicle weaknesses in the sections above.
Frequently Asked Questions
What problems and weaknesses does the BMW Z4 G29 have? +
What should I look for when buying a used BMW Z4 G29? +
Which engine is recommended? +
Which BMW Z4 G29 engine is the most fun? +
Is the BMW Z4 G29 worth buying used? +
What horsepower variants are available for the BMW Z4 G29? +
Last updated: February 2026 · All information without guarantee