BMW 8 Series: Best Years and Years to Avoid
The modern 8 Series is a single-generation grand tourer sold as the G15 coupe, G14 convertible and G16 Gran Coupe. It shares much of its running gear with the 5 and 7 Series, so the buying logic is familiar: the straight-six 840i and 840d are the sensible choices, while the V8 M850i is fast but maintenance-heavy. None of the body styles is a blanket avoid, but the engine you choose decides your running costs.
Quick answer
Best all-round pick: an 840i (B58) petrol or 840d (B57) diesel. Be most careful with the V8 M850i (N63) unless its history is fully documented. The six-cylinder engines are the durable heart of the range; the V8 rewards only well-documented, deep-pocketed buyers.
G15 / G14 / G16 (2018-present) Mixed
Chassis: G15, G14, G16
The 8 Series is a modern grand tourer that is dependable on its six-cylinder engines and expensive on its V8. The 840i (B58) and 840d (B57) share proven units with the 5 and 7 Series and age well; the M850i (N63) is rapid but carries the usual V8 cost caveats. Whichever body style you choose, the engine decision matters most.
| Best years | Any 840i (B58) or 840d (B57) with full history is the sensible buy. Later cars benefit from accumulated software updates; the diesel suits higher-mileage grand touring. |
| Years to watch | M850i (N63 V8) cars for coolant, timing-chain-guide and oil-consumption issues, and every convertible (G14) for correct powered-roof operation. |
| Engines to trust | 840i (B58), 840d (B57) |
| Engines to check | M850i (N63 V8), M8 (S63 V8, hard-used examples) |
Key risks
- N63 V8 (M850i): coolant transfer pipe, timing chain guides and high oil consumption
- B57 diesel (840d) DPF regeneration needs; avoid short-trip-only cars
- S63 V8 (M8): high running costs and scrutiny on track-used cars
- Large alloys, adaptive suspension and, on the G14, the powered roof: verify all operate correctly
The pick of the range
The sensible 8 Series is a six-cylinder car. An 840i (B58) is the pick for most buyers: one of BMW's most dependable modern petrol engines in a refined grand tourer. If you cover big motorway miles, the 840d (B57) diesel adds long-legged economy from an equally durable straight six. Choose the body style (G15 coupe, G14 convertible or G16 Gran Coupe) on taste; the mechanical advice is the same across all three.
What to avoid, and why
The engine to approach with most caution is the V8 M850i (N63), which shares the coolant transfer pipe, timing-chain-guide and oil-consumption tendencies of BMW's other N63 cars. The M8 (S63) is a specialist ownership with high running costs, especially on track-used examples. Neither is an automatic walk-away, but both should be bought only with full history and a serious maintenance budget. On any car, confirm the adaptive suspension, large alloys and powered roof are all in good order.
Check a specific 8 Series listing
Paste any BMW 8 Series listing, VIN, or registration. Bimmer.AI returns an engine-specific buyer report in 30 seconds. £7 per report, no subscription.
Get your report →Bimmer.AI is designed to help you identify BMW-specific buyer risks before you travel, negotiate, or pay for an inspection. It does not replace a physical inspection by a qualified mechanic, a legal vehicle-history check (e.g. HPI Check), or independent verification of finance, stolen, or write-off status. Repair-cost ranges are indicative UK figures that vary by region, specialist, parts supply, and labour rates.
Frequently asked questions
What is the most reliable BMW 8 Series engine?
The 840i (B58) petrol and 840d (B57) diesel are the most reliable choices. Both are proven straight sixes shared with the 5 and 7 Series and age well, avoiding the higher running costs of the V8 M850i (N63) and M8 (S63).
Which BMW 8 Series should I avoid?
No body style is a blanket avoid. The engine to treat with most caution is the V8 M850i (N63), which carries coolant, timing-chain-guide and oil-consumption risks. Buy one only with full history and a maintenance fund.
Is the BMW 840i reliable?
Yes. The 840i uses the B58 straight six, one of BMW's most dependable modern engines. Routine servicing plus checks on the charge pipe, cooling and adaptive suspension keep it a sensible grand tourer, and it is the pick of the range for most buyers.
Is the M850i (N63) reliable?
The N63 V8 is powerful but maintenance-heavy, with documented coolant transfer pipe failures, timing chain guide wear and high oil consumption. It can be owned successfully with full history and a repair budget, but it is not a cheap car to keep.
Petrol or diesel 8 Series for the UK?
For long-distance grand touring, the 840d (B57) diesel offers strong economy and torque from a durable six. If your mileage is lower or you prefer petrol refinement, the 840i (B58) is equally dependable and avoids DPF concerns.
Is the 8 Series coupe, convertible or Gran Coupe the best buy?
Mechanically they are the same car, so choose on practicality and taste: the G15 coupe for looks, the G14 convertible for open-top driving, and the G16 Gran Coupe for four doors and more space. On any convertible, verify the powered roof works through a full cycle.