Most of Europe's used diesels are imported from Germany and the Netherlands, and reliability swings wildly between generations of the same engine family. A Volkswagen TDI can be a million-kilometre legend or a money pit depending on which one you buy. This guide ranks the diesels worth owning — and flags the ones that will empty your wallet — using EngineScope's reliability scores, the models each engine powers, documented failure modes, and real repair costs.
Every score below comes from the engine's documented issues, repair-cost data, and failure patterns. Click any engine for its full report.
The most reliable diesel engines
| Rank | Engine | Brand | Score | Verdict |
|---|---|---|---|---|
| 1 | OM606 | Mercedes-Benz | 96/100 | BEST |
| 2 | 1.9 TDI (ALH/AHF/ASV) | Volkswagen | 92/100 | BEST |
| 3 | OM648 | Mercedes-Benz | 90/100 | BEST |
| 4 | OM654 | Mercedes-Benz | 85/100 | BEST |
| 5 | 1GD-FTV | Toyota | 85/100 | BEST |
| 6 | M57 | BMW | 84/100 | BUY |
| 7 | 1.5 dCi (K9K) | Renault | 82/100 | BUY |
| 8 | OM642 | Mercedes-Benz | 82/100 | BUY |
| 9 | 3.0 V6 TDI | Audi | 80/100 | BUY |
| 10 | 1.6 CRDi (D4FB) | Hyundai/Kia | 80/100 | BUY |
| 11 | B47 | BMW | 80/100 | BUY |
| 12 | 2.0 TDI CR (EA189/288) | Volkswagen | 78/100 | BUY |
| 13 | Skyactiv-D 2.2 | Mazda | 78/100 | BUY |
| 14 | 2.0 HDi (DW10) | PSA | 78/100 | BUY |
See the full list on the Best Diesel Engines page.
The legends
OM606 (Mercedes-Benz) — 96/100 → The benchmark. Mercedes' 3.0 inline-six diesel from the 1990s is mechanical, over-built, and routinely passes 500,000 km. The pre-electronic versions are the most bulletproof diesel ever scored here. Found in: Mercedes-Benz 300D, E 300D (W124 / W210).
1.9 TDI ALH/AHF/ASV (Volkswagen) — 92/100 → The people's million-kilometre engine. Simple pump-injector design, no DPF, no timing chain to fail — the single most reliable diesel in the mainstream used market. Found in: VW Golf, Passat, Polo, Touran; Audi A3, A4, A6; SEAT Ibiza, Leon, Alhambra; Škoda Octavia, Fabia, Superb.
OM648 (Mercedes-Benz) — 90/100 → Mercedes' refined straight-six common-rail diesel (E 320 CDI era). Found in: Mercedes-Benz C-Class, E-Class, S-Class.
OM654 (Mercedes-Benz) — 85/100 → Proof Mercedes fixed its diesels. The 2016+ workhorse and the engine to look for in a recent used diesel. Found in: Mercedes-Benz A-Class, C-Class (C 220d), E-Class (E 220d), CLA, GLA, GLC, GLE, S-Class.
1GD-FTV (Toyota) — 85/100 → Toyota's modern 2.8 diesel — built for places without dealerships, which is exactly why it scores so high. Found in: Toyota Hilux, Land Cruiser, Avensis.
Safe modern buys
If you want something from the last 15 years rather than a classic, these earned a BUY verdict:
- BMW M57 — 84/100 → — the good BMW diesel six, before the N47's chain problems. In: 3, 5, 7 Series, X5.
- Renault 1.5 dCi K9K — 82/100 → — Europe's most common small diesel. In: Renault Clio, Megane, Captur, Kadjar, Scenic; Dacia Duster, Sandero, Logan; Nissan Qashqai, Juke, Micra, X-Trail.
- Mercedes OM642 — 82/100 → — the 3.0 V6 diesel across the Mercedes range. In: C-Class, E-Class, S-Class, CLK, GLE, ML, G-Class.
- Audi 3.0 V6 TDI — 80/100 → — strong and refined. In: Audi A4, A5, A6, A7, A8, Q5, Q7; VW Touareg.
- Hyundai/Kia 1.6 CRDi D4FB — 80/100 → — the dependable Korean diesel; watch DPF health on city cars. In: Hyundai i20, i30, Tucson, Santa Fe, Kona; Kia Ceed, Sportage, Rio, Soul.
- BMW B47 — 80/100 → — the engine that replaced the troubled N47 and fixed the chain. In: BMW 1, 2, 3, 4, 5 Series, X1, X3, X5.
- VW 2.0 TDI CR (EA288) — 78/100 → — the common-rail 2.0 TDI; far better than the older PD units. In: VW Golf, Passat, Tiguan; Audi A3, A4, A6, Q5; SEAT Leon; Škoda Octavia, Superb, Kodiaq; Porsche Macan.
- Mazda Skyactiv-D 2.2 — 78/100 → — efficient and refined; keep up with oil changes. In: Mazda 2, 3, 6, CX-3, CX-5, CX-30, CX-60.
Diesels to avoid
These have documented, expensive failure modes. Walk away — or negotiate hard.
- JLR Ingenium 2.0D pre-2019 — 28/100 → — the lowest-scoring diesel here. In: Jaguar XE, XF; Land Rover Discovery Sport, Range Rover Evoque.
- BMW N47 — 35/100 → — the infamous rear-mounted timing chain. When it fails it destroys the engine, and replacement runs €2,500–6,000 because the gearbox must come out to reach it. EGR and DPF problems pile on another €500–1,200. In: BMW 1, 3, 5 Series, X1, X3; MINI Cooper, Countryman, Clubman.
- Mercedes OM651 (early) — 38/100 → — early versions had injector and timing-chain issues; the later OM651 and the OM654 are far safer. In: Mercedes A-, B-, C-, E-Class, CLA, GLA, GLC, GLE, GLK.
- VW V10 TDI 5.0 — 38/100 → (in: VW Touareg) and VW/Audi 2.5 V6 TDI — 40–42/100 → (in: VW Passat, Touareg; Škoda Superb) — complex, costly, and not worth the risk on the used market.
What to check before buying any used diesel
- Short-trip history kills diesels. A DPF needs motorway runs to regenerate. A car driven only around town will clog its DPF — a €400–1,200 job on a Hyundai/Kia 1.6 CRDi, more on others.
- Know where the timing chain lives. Rear-mounted chains (BMW N47) are the expensive ones. Belt-driven engines like the 1.9 TDI are cheap to service.
- Look for EGR and injector service records. EGR fouling is the most common moderate-cost diesel fault across almost every family here.
- Match the engine to your use. Buy a diesel only if you drive long distances regularly. For short urban trips, a reliable petrol or hybrid will cost you far less in the long run.
Check any engine's full issue list, repair costs, and mileage risk timeline on its EngineScope report before you buy.