N47 vs N57 — Which BMW Diesel Engine Should You Buy?

For most buyers, the N57 is the better engine if you need the six‑cylinder torque and refinement — it's more powerful, smoother, and suits larger cars like the 5 Series, X5, and 3 Series 330d. The N47 is the cheaper, more economical choice for smaller cars, but its timing chain risk is well‑documented. Both have known weaknesses, but the N57's extra cylinders make it a more rewarding drive.

N47: 1,450 enquiries in 2025, £3,200–£5,500 recon supply [EM-VERIFIED / EM-QUOTE]
N57: 830 enquiries in 2025, £4,500–£7,000 recon supply [EM-VERIFIED / EM-QUOTE]
N47 timing chain failure risk at 60–120k miles; N57 chain stretch and turbo issues also known
N57 delivers significantly more torque and refinement, especially in 3.0L form
Over a five‑year ownership, the N57 typically costs more to run but offers a better driving experience

Full spec comparison, five‑year cost of ownership, the case for each engine, and which to choose for your situation below.

At a Glance

	BMW N47 (2.0L 4‑cyl diesel)	BMW N57 (3.0L 6‑cyl diesel)
Displacement	2.0L turbo diesel	3.0L turbo diesel
Cylinders	4	6 (inline)
Power (typical)	116–204 bhp	204–313 bhp
Torque (typical)	260–400 Nm	400–630 Nm
Primary Models	1, 3, 4, 5 Series (diesel), X1, X3	3, 5, 6, 7 Series, X3, X5, X6
2025 UK Enquiries	1,450 [EM-VERIFIED]	830 [EM-VERIFIED]
Typical Host Value	£3,000–£9,000 [THIRD-PARTY]	£8,000–£25,000 [THIRD-PARTY]
Recon Supply Cost	£3,200–£5,500	£4,500–£7,000
R&R Labour	10–14 hrs	12–16 hrs
Defining Failure	Timing chain guide failure	Timing chain stretch / turbo wear
Best For	Smaller cars, economy, urban use	Larger cars, motorway cruising, towing

The Verdict

For most buyers, the N57 is the stronger choice if you need performance and refinement — it generates fewer enquiries (830 vs 1,450) because it's fitted to fewer cars, but when it fails, the cost is higher. The N47 is cheaper to buy and run, but the timing chain issue is a genuine risk. In a 3 Series, the N57 (330d) is the sweet spot; in a 1 Series, the N47 (120d) is more than adequate. The decision comes down to your budget, your car size, and your tolerance for risk.

N47 Deep Dive

The N47 is BMW's most‑produced diesel engine, found in everything from the 1 Series to the 5 Series. It offers impressive economy and adequate power for most drivers. Its main weakness is the timing chain guide — the plastic guides can become brittle and fail, leading to catastrophic engine damage. This is particularly prevalent on pre‑2011 engines. A preventative chain replacement costs around £1,500‑£2,500 [EM-QUOTE]. At £3,000–£9,000, the N47 is a cheap entry point, but you're buying an engine with a known risk. Full specs, fitment and reliability rating live on the N47 Knowledge Centre.

N57 Deep Dive

The N57 is the six‑cylinder diesel that powers the 330d, 530d, X5 30d and many more. It's smooth, powerful, and torquey — a true motorway cruiser. Its main weaknesses are timing chain stretch (less common than the N47's guide failure) and turbocharger wear on higher‑mileage examples. A chain replacement on the N57 is more expensive, at around £1,500‑£2,500 as well, but the labour is more involved. The N57 is a much more refined engine, and its extra torque makes a real difference in larger cars. Full specs and fitment on the N57 Knowledge Centre.

Five-Year Ownership Cost

The practical cost difference between these two engines over five years is driven by three factors: depreciation, running costs, and the probability of a major engine failure. The N57 will cost more to buy but will retain more of its value — a well‑maintained 530d will still be worth £6,000+ after five years, while a 320d will have dropped to around £3,000. Running costs are better on the N47 — it delivers 50+ mpg on a motorway run, while the N57 struggles to hit 45 mpg. The probability of a major failure is similar, but the N57's higher replacement cost (£4,500–£7,000 supply) and labour times mean a failure is more expensive. The N47's lower host value can make a chain failure a write‑off, while the N57's higher value makes repair more viable.

Which Should You Buy?

🚙

Buying a 1 Series or 3 Series (smaller car)

Go N47 (120d/320d) — it's economical, cheap to run, and offers more than enough power for daily driving. Just budget for a chain replacement if buying pre‑2011.

🏔️

Buying a 5 Series, X5, or large car

Go N57 — the torque and refinement are essential in a heavier car. The extra cost is worth it for the driving experience, and the higher host value makes repair more viable.

💰

Prioritising Lowest Running Cost

N47, decisively — better fuel economy, cheaper parts, and lower insurance groups. The N57 is a thirstier engine.

🔁

Buying to Keep Long-Term

If you plan to keep the car for many years, the N57's smoother, more robust character makes it a better companion, provided you maintain it well. The N47 is fine but the chain risk is always there.

One point worth being explicit about: the N47 is not a bad engine — it's actually very good when maintained. But the timing chain issue is a genuine design flaw that can be expensive to fix. The N57 is a significantly better engine in every measurable way, but it costs more to buy and run. The decision genuinely comes down to budget and what you want from the car.

Other Diesel Comparisons

If you're still narrowing down which BMW diesel to buy, these cover the other most‑asked pairings.

N47 vs B47 →

The older N47 against its successor.

N57 vs B57 →

The six‑cylinder diesels compared.

N47 vs N57 →

You're already here!

Diesel vs Petrol →

Fuel type running costs compared.

Whichever engine you choose, the same repair vs replace framework applies to the replacement decision once you've bought the car.

Frequently Asked Questions

Is the N57 better than the N47?

For most buyers, yes — the N57 is smoother, more powerful, and more refined. The N47 is the more economical choice, but its timing chain risk makes it a risk. The N57 is the better engine for larger cars and long‑distance driving.

Which BMW diesel is more reliable, N47 or N57?

Both have known issues — the N47 has timing chain guide failure, while the N57 has chain stretch and turbo problems. The N57 is generally considered more robust, but neither is bulletproof. A well‑maintained example of either can be reliable.

Is the N47 cheaper to run than the N57?

Yes — the N47 delivers better fuel economy (50+ mpg vs 45 mpg) and has cheaper parts. However, the N57 offers a much better driving experience, especially in larger cars.

Which is better, N47 320d or N57 330d?

The N57 330d is the better car — it's more powerful, smoother, and more refined. The 320d is more economical and cheaper to buy. The 330d is the sweet spot in the 3 Series range.

Which is easier to replace when it fails, N47 or N57?

Both are relatively straightforward, but the N47's lower host value makes replacement less financially viable. The N57's higher value makes a £4,500+ engine replacement a more sensible proposition.

✓

2,280 Combined EnquiriesBoth engines analysed from real 2025 UK data.

✓

A Real VerdictWe name a winner, and explain honestly when the "loser" is still the right choice.

✓

20+ Vetted BMW SpecialistsExperienced with both engines.

✓

100% IndependentNo sponsors, no manufacturer influence.

N47 vs N57 — Which Should You Buy?