The BMW 3 Series is the sports saloon benchmark that every other manufacturer measures itself against. The E90 generation has 33 approved fault entries in the MyCarFault database with 168,783 combined views β the highest view total of any individual model in the database. This is not because the 3 Series is particularly unreliable. It is because it is one of the most popular used cars in the world and its faults attract intense public attention.
This Buying Guide guide combines structured analysis β verdicts, risk scoring and cost ranges where we have enough data β with real fault cases pulled directly from MyCarFault's reporting database, so the guidance below reflects what owners actually experience rather than manufacturer specifications alone. Background and analysis come first, followed by the linked fault reports and related guides you can jump to directly using the links above.
A used BMW 3 Series is not a single buying proposition β it is a branching decision tree where engine choice determines almost everything about the risk profile and long-term cost. A BMW 3 Series with the N52 naturally aspirated petrol or the B47 diesel is a competent, enjoyable and broadly reliable used car. A BMW 3 Series with the N47 diesel is a car that requires specific, verified, documented evidence of timing chain replacement before purchase can be justified. These are not two versions of the same buying decision with different trade-offs. They are fundamentally different propositions. Every other consideration β colour, spec, service history frequency β is secondary to the engine code.
The N52 straight-six petrol β 325i and 330i β is widely regarded as one of BMW finest naturally aspirated engines. It is smooth, characterful, durable with correct servicing and free of the catastrophic failure modes present in the diesel lineup. High-mileage N52 engines with full service histories are genuinely desirable used cars. The N46 four-cylinder petrol (318i, 320i) is less exciting but similarly robust β no catastrophic failure mode, manageable maintenance costs. The N47 diesel (316d, 318d, 320d) must be treated as described in the timing chain guide. Buy only with documented chain replacement or after factoring in the cost of immediate preventive work. The N54 twin-turbo petrol in the 335i is a performance engine with its own concerns β HPFP failure being the most documented β but it does not carry a catastrophic systemic failure risk equivalent to the N47.
BMW addressed the N47 chain problem with the B47 diesel introduced for the F30. The chain moves to the front of the engine, the tensioner design is revised and the oil delivery to the chain is improved. Owner-reported failure rates on the B47 are significantly lower than the N47 and the community consensus treats the B47 as a solid diesel choice. The F30 with the B47 is a better daily-use car than the E90 with N47 by a meaningful margin on reliability grounds. The B48 2.0 petrol in the F30 is a fine engine with one known concern: the electric water pump can fail silently. This is a manageable risk with awareness, not a systemic concern. Budget for water pump replacement as a preventive measure at 100,000 km on any B48-equipped car.
Buy with inspection β and with engine code verified. An N52 or B47 3 Series with a competent service history is one of the most satisfying used driver cars available. An N47 diesel with unknown chain history is a lottery. The buying decision is not about the badge β it is about which engine is under the bonnet and what paperwork accompanies it.
On diesel, yes β the B47 is materially better than the N47. On petrol, both N52 (E90) and B48 (F30) are broadly comparable, with different specific concerns. The F30 is more refined; the E90 is considered the more engaging driver car.
A well-maintained 3 Series owned by a competent independent BMW specialist typically costs Β£600-1,200 per year in routine maintenance. Budget additionally for major services every 2-3 years (Β£400-800).
The S65 V8 in the E92 M3 is a remarkable engine with specific rod bearing concerns on early units. The S55 in the F80 M3 is broadly stronger. Both are specialist purchases with higher maintenance costs and a smaller competent servicing base.
For oil changes and basic consumables, yes. For fault diagnosis, software updates, VANOS work, transmission adaptation and any electronic module replacement, a BMW-capable specialist is necessary.
Link to: /common-problems/bmw-3-series | /engines/bmw-n47-timing-chain | /engines/bmw-n47-problems | /repair-cost/timing-chain-replacement-cost | /checklist/bmw-e90-pre-purchase-inspection