BMW i3s REx

First generation (60 Ah) shows significantly stronger degradation than 94/120 Ah. Remaining capacity sometimes below 70% after 8 years. Replacement is extremely expensive.

Symptoms: Reduced range, inaccurate state of charge display, battery warning

Some i3s develop grinding and rumbling noises from the drivetrain between 45,000 and 60,000 km. Cause is a bearing failure in the reduction gearbox or e-motor bearing set. Replacement of the complete drive unit is often unavoidable.

Symptoms: Grinding or rumbling noise at low speed; noise intensifies under load; no dashboard warning in early stages.

On the i3 REx, the timing chain tensioner spring on the two-cylinder boxer engine (same as BMW C600 scooter engine) breaks. The chain jumps, intake valves bend. BMW issued a recall for scooter models but not for the i3 REx.

Symptoms: REX shuts itself off, only electric drive available; fault 'Camshaft sensor implausible'; misfires on cylinders 1 and 2.

From around 60,000 km, i3 batteries measurably lose capacity. In winter the effective range drops to 80–100 km (60 Ah variant) as heating and cold losses compound. After 10 years, 20–25% capacity loss is typical.

Symptoms: Noticeably lower displayed range in winter; car doesn't reach displayed range; GOM estimate fluctuates heavily in cold.

When releasing the accelerator, the expected engine braking is occasionally absent; the car coasts without regeneration. Caused by a software fault in the drive control, occurring at full battery or after temperature changes.

Symptoms: Car coasts when lifting off instead of regenerating; no braking effect felt; occurs sporadically, often after charging to 100%.

The i3's CFRP carbon fibre body quickly leads to an economic total loss after accidents. Even minor damage to the passenger cell life ring can only be repaired at specialist BMW workshops and costs many times more than a steel body.

The electric machine electronics (EME) can fail from internal hardware faults. Sudden power loss while driving, vehicle can no longer move. Repair requires complete removal of the rear axle.

Early i3s (22 kWh, up to 2017) without active thermal management show stronger battery degradation. From 2017 (33 kWh) under 5% per year is expected. BMW new battery price approximately 12,000–14,000 € including fitting.

On the i3 REx, problems occur with engine mounts, charging electronics, the fuelling system, and the generator of the small 2-cylinder combustion engine. Exhaust system can also fail prematurely.

The i3 I01 charging port can fail to lock correctly or get stuck locked. Wear of the locking motor and contact pins is a known issue on older vehicles.

The comfort charging electronics (KLE) control AC charging and can fail after several years. AC charging rate drops significantly or stops completely. Repair costs 1,200–2,000 €; BMW occasionally offers goodwill.