The BMW i8 is a plug-in hybrid sports car with a CFRP passenger cell, butterfly doors, and a mid-mounted 1.5-litre turbo three-cylinder driving the rear wheels alongside a front-axle electric motor for all-wheel drive. It was built in limited numbers, and this report covers both the I12 Coupé (from 2014) and the I15 Roadster (from 2018); the 2018 update increased battery capacity from 7.1 to 11.6 kWh and raised combined output from 362 to 374 PS.· more· less
Robust B38 engine and electric motorCFRP body eliminates corrosion risk
HV AC compressor failure can be costlyLimited specialist availability
Buy if: You want a unique hybrid sports car with genuine performance and can budget for specialist maintenance and the occasional expensive HV system repair.
Avoid if: You need widely available parts and generic workshop support, or cannot absorb repair bills above €3,000 for high-voltage component failures.
Internal scroll failure scatters metal debris through the entire HV cooling circuit · more· less
The i8 uses a high-voltage electric AC compressor that cools both the cabin and the high-voltage battery pack. When the internal scroll mechanism fails, it can disintegrate and send metal shavings through the sealed refrigerant circuit, contaminating the condenser, evaporator, and battery cooling lines. A simple compressor swap costs around €2,500 at a specialist. If debris has contaminated the HV battery cooling loop, the entire system must be flushed or replaced, and repair bills can reach €8,000 or more. This issue is more common on 2014-2015 models and has been the subject of BMW technical service bulletins. If you hear grinding from the AC system, stop driving immediately to prevent the contamination from spreading.
KLE charging module failure
up to €3,0002 of 7
Onboard charger fails, preventing the HV battery from charging via the plug · more· less
The KLE (Komfort-Ladeelektronik) module is the onboard AC charger shared across BMW PHEV models including the i8, 330e, and 530e. When it fails, the car displays charging errors or simply refuses to charge through the plug. The car still drives normally using the petrol engine and regenerative braking, but electric-only range is gradually lost. The KLE unit must be coded to the vehicle VIN after replacement, so only a BMW dealer or specialist with ISTA diagnostic access can complete the repair. Parts cost approximately €800-1,500 and labour adds €500-1,000 depending on the workshop. Reports from 330e and 530e forums suggest this typically occurs between 60,000 and 120,000 km.
Windscreen stress crack
up to €3,0003 of 7
Windscreen develops cracks without stone impact, often while parked · more· less
The i8 has a well-documented pattern of windscreen stress cracks that develop without any visible impact damage. Multiple Bimmerpost threads describe cars stored in garages developing large cracks overnight. The cause is believed to be related to the windscreen bonding process: insufficient or incorrectly applied sealant positions the glass too close to the frame, and thermal stress from temperature changes triggers the fracture. BMW covered some cases under warranty when no stone impact was evident, but used car buyers are unlikely to have this recourse. Replacement windscreens for the i8 are expensive due to the unique shape and integrated technology. Independent glass shops quote €1,500-2,000, while BMW dealers charge up to €3,000 including calibration of driver-assistance sensors.
12V auxiliary battery drain
up to €5004 of 7
12V battery discharges when the car sits for more than a week, preventing startup · more· less
Like many BMWs, the i8 draws significant standby current from its 12V system even when parked. The complex hybrid control units, telematics, and security systems collectively drain the small 12V battery within 7-14 days of inactivity. The car may then refuse to start or show multiple warning messages. This is a characteristic of the model rather than a defect. A quality trickle charger (CTEK MXS 5.0 or similar) is essential for any i8 that is not driven daily. Battery replacement costs €200-350 for the 12V unit. A failing Intelligent Battery Sensor (IBS) can exacerbate the problem by mismanaging charge regulation, adding another €100-200 to the repair.
Coolant system leak
up to €1,5005 of 7
Coolant hoses, thermostat housing, or connections develop leaks, typically after 60,000 km · more· less
The i8 has a complex cooling system with multiple circuits serving the combustion engine, electric motor, power electronics, and HV battery. Plastic-bodied coolant connections, hoses, and thermostat housing components can develop leaks as they age and undergo thermal cycling. Symptoms include coolant warning lights, visible puddles, or reduced cabin heating. Because the engine is mid-mounted and access is restricted by the CFRP tub, labour times are higher than on a conventional BMW. Independent specialists typically charge €500-800 for hose and connection repairs, while thermostat housing replacement can reach €1,000-1,500 at a dealer.
Fuel filler cap and pressure sensor failure
up to €8006 of 7
Pressurised fuel system prevents the fuel door from opening at the pump · more· less
The i8 pressurises its entire fuel system, and when you press the fuel door release, the dashboard displays a Preparing to Refuel message while the system depressurises. If the fuel tank pressure sensor fails, this process stalls and the fuel door remains locked. This can leave you stranded at a petrol station. An emergency release cable in the boot provides a temporary workaround. BMW issued a service bulletin for the pressure sensor, and replacement costs €300-500 at a specialist. In some cases, the fuel pump assembly (which integrates the pressure sensor) requires replacement at €500-800.
The oil level sensor on the B38 can produce false readings, triggering persistent low-oil warnings on the dashboard even when the oil level is correct. This is a nuisance rather than a safety concern, but it can mask genuine low-oil conditions if the driver becomes accustomed to dismissing the warning. The ultrasonic sensor degrades gradually, often after exposure to short-trip driving or extreme temperature cycles. Replacement costs €200-400 including labour and typically resolves the issue permanently.
Reliable drivetrain, but exotic repair costs when HV components fail
The B38 three-cylinder and the electric motor are both robust units, and many i8s exceed 100,000 km without major powertrain issues. The main ownership risks centre on the high-voltage system: the electric AC compressor can contaminate the entire cooling circuit if it fails catastrophically, and the KLE charging module is a known weak point across BMW PHEVs. The CFRP body eliminates traditional corrosion concerns but limits which workshops can perform structural repairs. Windscreen stress cracks and the pressurised fuel system are well-documented i8-specific issues. Keep the 12V battery on a trickle charger when the car is parked for more than a few days.
Service history
Complete BMW dealer or i8 specialist records essential. Verify all scheduled services including door hinge and HV system checks.
Test drive
Minimum 30 minutes including motorway speeds. Drive in all modes (Comfort, Sport, eDrive) and monitor for warning messages.
Cold start
Start the car completely cold. Listen for unusual noises from the engine bay and check that the electric motor engages smoothly.
Tire condition
Check the 20-inch tires for tread depth, sidewall damage, and date codes. Standard sizes are 195/50 R20 front and 215/45 R20 rear; the optional wheels use 215/45 R20 front and 245/40 R20 rear. These are expensive to replace.
Specific for this vehicle
Test HV charging system thoroughly
Plug the car in and verify that charging starts within 30 seconds. Watch for error messages or repeated disconnections, which indicate KLE module failure.
Inspect windscreen for stress cracks
Examine the entire windscreen carefully in good light. Look for hairline cracks originating from the edges without any impact mark. Replacement is €1,500-3,000.
Check butterfly door operation
Open and close both doors multiple times. They should lift smoothly without resistance, sagging, or unusual noises. Check the door hold position and locks.
+ 5 more checksShow less
Test fuel filler cap release
Press the fuel door release and wait for the Preparing to Refuel message to clear. If the door does not open, the pressure sensor or actuator has failed.
Verify all recalls completed
Check with BMW using the VIN. Campaigns listed for the i8 cover the EPS control unit (A12/1587/16, 2014-2016 production), the DSC hydraulic unit (A12/0057/16, built 29 May to 5 June 2015), the power electronics (A12/0092/16, built 9 October to 4 November 2015) and the high-voltage battery (A12/01680/20; UK R/2020/283, i8 built 18 May to 3 June 2020).
Check 12V battery condition
Measure 12V battery voltage with engine off. Should read above 12.4V. Ask how often the car sits unused and whether a trickle charger is used.
Inspect coolant levels in all circuits
Check the expansion tank. Low coolant or discolouration points to leaks in the complex multi-circuit cooling system. Check under the car for drips.
Test electric roof mechanism (Roadster only)
Operate the two-piece folding roof several times. It should open and close fully without hesitation, binding, or warning messages.
Recalls and Technical Service Bulletins
Electronic power steering control unit fire risk (A12/1587/16, production 2014-2016)Verify completed
Manufacturing fault in the DSC hydraulic unit can impair stability control in critical driving situations (EU Safety Gate A12/0057/16, built 29 May to 5 June 2015)Critical - verify completed
Incorrectly calibrated power electronics can increase regenerative braking torque when decelerating, with a risk of skidding on slippery roads (EU Safety Gate A12/0092/16, i3 and i8 built 9 October to 4 November 2015)Critical - verify completed
High-voltage battery cell contamination, short-circuit and fire risk (EU Safety Gate A12/01680/20: BMW and MINI plug-in hybrid models including the i8, multi-model build window 5 February to 2 October 2020, while i8 production ended on 11 June 2020; UK DVSA R/2020/283: i8 built 18 May to 3 June 2020)Critical - verify completed
Contact BMW with the VIN to verify that every listed campaign has been completed. Listed for the i8: the electronic power steering control unit campaign (A12/1587/16, 2014-2016 production), the DSC hydraulic unit campaign (A12/0057/16, built 29 May to 5 June 2015), the power electronics campaign (A12/0092/16, built 9 October to 4 November 2015) and the high-voltage battery campaign (EU Safety Gate A12/01680/20; in the UK, R/2020/283 names i8s built 18 May to 3 June 2020, and i8 production ended on 11 June 2020). Whether a particular car is affected depends on its VIN, so have a BMW dealer check the complete recall history by VIN before purchase.
Warranty Status
Germany: 24 months statutory Gewährleistung, plus BMW's 12-month 2+1 extension from November 2016Expired on all used i8s
UK: 3-year BMW warrantyExpired on all used i8s
HV battery (Germany: 8 years / 100,000 km; UK: 8 years / 100,000 miles)Check remaining term with BMW dealer
Extended warranty (Germany: BMW Repair Inclusive)Ask a BMW dealer about eligibility
All i8s are outside their original factory cover, which in Germany was 24 months of statutory Gewährleistung, plus BMW's 12-month 2+1 extension from November 2016, and in the UK a three-year BMW warranty. The high-voltage battery warranty runs 8 years from first registration, limited to 100,000 km in Germany or 100,000 miles in the UK, so it may still be active on later cars. Verify remaining HV battery coverage with a BMW dealer using the VIN before purchase.
Sources: Research draws on model-specific owner forums and owner communities, recall information from official authorities, German automotive press, and multiple workshop cost references cross-checked against each other.
This report is for informational purposes only and does not constitute professional advice. Estimates may be inaccurate. Always have a qualified specialist inspect the vehicle before purchase. We accept no liability for decisions made based on this information.
