Which 5 Series BMWs Are The Most Reliable? Clearly Explained By Engine Type
Image: BMW B58 engine for sale at mtautoparts.com
Ask BMW owners which 5 Series is the most reliable, and the answers quickly start to conflict. Some swear by diesels, others won’t touch anything without petrol, and plenty will tell you reliability depends on luck when buying a used BMW.
Most commonly, it all depends on something far more specific: the engine design.
Across the E60, F10 and G30 generations, BMW used very different engines under the same 5 Series badge. Some have proven remarkably durable in everyday use. Others demand far more care and cost as the miles add up.
This guide looks at reliability where it actually lives: engine by engine, not brochure labels.
Why the Engine Matters More Than the Model Year
BMW evolves engines over long production cycles. The same engine can appear across multiple generations, while a single generation can contain both excellent and problematic units.
That’s why judging reliability by age or facelift alone often misses the point. Two visually identical 5 Series cars can have completely different long-term ownership experiences depending on what’s under the bonnet.
BMW’s Most Reliable Modern Petrol Engine
The B58 Six-Cylinder
If there’s one modern BMW petrol engine that consistently earns praise, it’s the B58.
Found in later 5 Series such as the 540i and 545e plug-in hybrid models, it combines strong performance with a design that prioritises durability. Owners report smooth operation well into higher mileages, provided servicing is kept sensible rather than stretched.
What makes it stand out is not just power, but balance. Cooling, internal strength and real-world tolerance for daily driving were all improved over earlier designs. It’s one of the rare BMW engines that satisfies enthusiasts and long-term owners alike.
Reliability verdict shortly: excellent.
The Sensible Petrol Option Many Overlook
The B48 Four-Cylinder
The B48 doesn’t attract much attention, and that’s precisely why it deserves mention.
Used in 520i and 530i models, it focuses on efficiency and simplicity rather than outright performance. Fewer cylinders, fewer stresses, and a layout that avoids many of the pitfalls seen in older turbo petrol units.
For drivers who simply want a comfortable 5 Series, this engine has proven to be reliable when serviced properly.
Reliability verdict: Strong and predictable.
BMW’s Best Modern Diesel
The B47
BMW’s diesel reputation took a hit in the past, but the B47 marked a clear turning point.
Used in later 518d, 520d, later F10 LCI and G30 models, it corrected earlier design weaknesses and delivered far better long-term reliability. While modern emissions systems still require proper use and servicing, serious mechanical failures are far less common than they were in the past.
For drivers who cover a lot of miles, the B47 has quietly proven itself as one of the most dependable diesel engines BMW has used in the 5 Series.
Reliability verdict: Very good for a modern diesel.
The B57 Six-Cylinder Diesel
The B57 is BMW’s modern six-cylinder diesel, found in models such as the 530d, 540d and M550d in later F10 LCI and G30 cars. From an engineering standpoint, it is a very robust engine. The block, crankshaft and internal components are strong, and when used as intended — regular long-distance driving with proper maintenance, the B57 is capable of very high mileages without internal failure.
Where ownership becomes more demanding is complexity. Advanced turbocharging, high-pressure fuel systems and modern emissions equipment increase running costs, and repairs can be expensive when problems arise. As a result, the B57 is not unreliable, but it is not a low-stress ownership choice either. It suits drivers who value torque, refinement and motorway comfort, and who understand the maintenance commitment that comes with BMW’s more sophisticated diesel engines.
Reliability verdict: Mechanically strong, but ownership costs reflect its complexity.
The Engine That Divides Opinion
The N47
No discussion of BMW reliability is complete without mentioning the N47.
Early versions became known for timing chain problems, especially when servicing wasn’t done properly. That reputation has stuck, even though it doesn’t tell the full story. Many engines were fixed or updated years ago, and later versions can be reliable.
With the N47, what matters most is its history. An engine that’s had the chain work done, or comes from a later revision, is very different from an early example that’s never been addressed.
Reliability verdict: Acceptable only with known updates.
Engines That Require More Commitment
BMW has never been afraid of ambitious engineering, and that shows in several 5 Series engines. While units like the B58 and B48 are widely seen as low-stress, dependable all-rounders, and the B47 stands out as BMW’s most reliable modern diesel, not every engine follows that pattern.
Engines such as the N55 and N20 can be reliable, but they are less forgiving if servicing slips, with reliability often depending on version and maintenance history. The N47 sits in a similar position: fine if updated, but far riskier in its early, untouched form. Larger six-cylinder diesels like the N57 and B57 are mechanically strong, yet their complexity means higher costs when issues arise.
At the other end of the spectrum, BMW’s V8s, particularly the N63 and high-performance S63 engine, deliver impressive power but demand expert care. Heat, complexity and tight tolerances mean these engines are reliable only when maintained meticulously and with the right expectations.
That’s why these engines weren’t highlighted as the most reliable choices. They can be dependable, but they suit owners who understand the commitment involved, rather than drivers looking for simple, low-stress ownership.
Reliability Is About More Than Design
Even the best engine won’t survive poor maintenance.
Across all 5 Series generations, the most reliable cars share a few common traits:
Sensible oil change intervals
Correct fluids and parts
Problems addressed early, not ignored
When engines do reach the point where replacement makes more sense than repair, many owners turn to BMW breaker specialists, such as MT Auto Parts, who deal with complete BMW engines daily and understand the importance of correct engine codes and compatibility.
So, Which 5 Series BMW Is the Most Reliable?
Based purely on long-term engine performance:
Best all-round petrol: B58
Best low-stress petrol: B48
Best economical modern diesel: B47
Best powerful diesel engine: B57
Proceed with caution: N47 (early versions)
There is no universally perfect 5 Series, but some engines clearly age better than others.
Final Thoughts
Reliability in the BMW 5 Series isn’t random, and it isn’t marketing-driven. It’s engineered. Owners who understand engine design, maintenance needs and known weaknesses tend to enjoy years of dependable use. Those who don’t often learn the hard way from their own history and mistakes. If you want a reliable 5 Series, start by choosing the right engine. Everything else follows from there.
Frequently Asked Questions
Which BMW 5 Series engine is the most reliable overall?
There isn’t a single answer for everyone, but the B58 petrol engine consistently stands out for long-term reliability, smooth performance and durability. For drivers covering higher mileages, the B47 diesel is also a strong choice when serviced properly.
Are BMW diesel engines reliable in the 5 Series?
They can be, but engine choice matters. The B47 is BMW’s most dependable modern diesel, while older units like the N47 can be reliable only if known issues, such as timing chain updates, have already been addressed. Larger diesels like the N57 and B57 are strong but more expensive to maintain.
Is the N47 engine really as bad as people say?
Not necessarily. Early N47 engines earned a poor reputation due to timing chain problems, but many were fixed or updated years ago. Later versions, or engines with documented chain work, can be perfectly usable for many miles ahead. History matters far more than the engine name alone.
Are V8 BMW engines unreliable?
V8 engines such as the N63 and S63 aren’t unreliable by design, but they are demanding. They run hotter, use more complex systems and require strict maintenance. They suit enthusiasts who understand the costs involved, rather than drivers looking for low-stress ownership.
Is petrol or diesel more reliable in the BMW 5 Series?
Both can be reliable, depending on use. Petrol engines like the B48 and B58 tend to suit mixed or lower-mileage driving, while diesels like the B47 are better for long motorway use. Problems usually arise when the engine doesn’t match the driving pattern.
Does model year matter more than engine type?
Engine type is usually more important than model year. BMW often uses the same engine across multiple generations, so two cars of different ages can have very similar reliability if they share the same engine.
What matters most for long-term reliability?
Regular servicing, sensible oil change intervals, and addressing issues early matter more than almost anything else. Even the most reliable BMW engine won’t survive neglect, while a well-maintained engine with a mixed reputation can still perform well for years.
When does engine replacement make more sense than repair?
If major internal issues arise, such as timing failures, bearing damage or repeated overheating, replacing the engine can often be more cost-effective than chasing repeated repairs. In those situations, knowing where to look for a BMW engine for sale that’s correctly matched, with a clear history and proper compatibility checks, becomes just as important as the repair itself.
Can a used BMW engine be reliable?
Yes, if it’s the right engine and properly matched. The key is knowing the exact engine code, understanding known weak points, and ensuring compatibility. A well-chosen used engine can offer many years of reliable use.
Disclaimer: This article is intended as general guidance based on common ownership patterns and industry experience. Reliability can vary depending on maintenance history, driving conditions, and vehicle specification. Always verify engine codes, service records, and compatibility before purchasing or replacing an engine. Professional inspection and advice are recommended before making repair or purchase decisions.
