BMW i8 (I12) Common Problems & Reliability
The BMW i8 is a futuristic plug-in hybrid sports car that still looks like a concept vehicle on the road today. Positioned as a technology showcase, it utilizes a lightweight carbon-fibre reinforced plastic (CFRP) tub, a small 3-cylinder turbo engine, and an electric motor to deliver sports car performance with eco-car emissions. In the UK, it has a dedicated enthusiast following, but requires specialist BMW 'i' technicians for any repairs, particularly regarding the high-voltage battery or complex hybrid drivetrain. It suits early-adopters and style-conscious buyers wanting a striking, unique daily-drivable sports car.
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Detailed fault breakdown, symptoms, and estimated repair bills by production year.
Most Common BMW i8 (I12) Faults & Repair Costs
Door Strut Failure
The lightweight carbon-fibre and aluminium dihedral butterfly doors rely on high-pressure gas damper struts hidden within the front wings. Over time, gas pressure escapes, causing the doors to drop unexpectedly or feel excessively heavy to lift.
Door drops shut or fails to stay locked at its highest open detent, Noticeably heavy effort required to lift door upwards, Creaking or groaning sound from wing strut cavity during door movement
- Open both doors on level ground and confirm they remain fully upright without sagging
- Check gas struts inside front wing aperture for oil misting or leakage
REx Fuel Pressure Sensor
The petrol fuel tank is pressurized and sealed to prevent petrol vapour emissions during pure EV driving. The electronic fuel tank pressure relief sensor or tank vent solenoid valve can fail, causing the iDrive system to lock the fuel filler flap closed.
"Preparing for refuelling: please wait" message hangs continuously on dash, Fuel filler flap remains locked and will not pop open at petrol stations, Check engine warning light with EVAP fuel tank pressure sensor fault codes
- Press fuel flap release button next to driver footwell and verify flap pops open within 5 seconds
- Check boot emergency pull cord release mechanism for fuel flap
Steering Rack Knock
The lightweight electromechanical steering rack mounted to the front carbon-aluminium subframe develops internal clearance play between the steering rack bar and thrust piece, producing hollow metallic knocking over minor road imperfections.
Rattling or clunking feedback felt through steering wheel over cobbles and low-speed road ruts, Vague or loose on-centre steering response, Metallic knocking when rocking steering wheel side to side with engine off
- Test drive over speed bumps and coarse asphalt listening for front-end hollow knocking
- Inspect front steering tie rods and check if revised steering rack thrust piece bush has been fitted
Buying a used BMW i8 (I12)? Always check for hidden finance and write-off history.
Mechanical problems are only half the battle. Over 1 in 3 UK used cars checked have unpaid finance or accident write-off records that could cause you to lose the car or thousands in value.