BMW 6 Series E64Convertible2004–2010
Every engine fitted to the E64 convertible — from the 3.0-litre N52 straight-six to the N62 V8 and the S85 V10 that powered the M6.
Real UK replacement costs, honest failure data, and the N62 valve-stem-seal issues that still haunt high-mileage V8 cars.
Backed by 256+ real UK E64 enquiries in 2025 [BMW-VERIFIED].
Engine Database
Every engine fitted to the E64 convertible — from the entry-level 630i six-cylinder to the range-topping M6 V10.
Overview
The E64 is the convertible body of BMW's second-generation 6 Series, launched in May 2004 as the direct successor to the E24 6 Series after a 14-year hiatus. It shared the E63 coupé's controversial Bangle-designed bodywork but added a fully automatic soft-top roof that could be operated at speeds up to 20 mph.
The engine range spanned from the 3.0-litre N52 straight-six to the 4.4-litre and 4.8-litre N62 V8s, a late-arriving twin-turbo 3.0-litre diesel, and the S85 V10 in the M6. A 2007 Life Cycle Impulse (LCI) brought revised styling, the 635d diesel, and the replacement of the N52 with the N53 in the 630i.
Key Facts
Market Intelligence
The E64 convertible generated 256 real UK engine enquiries in 2025 [BMW-VERIFIED], concentrated on the N62 V8 petrol units as these grand tourers age into enthusiast ownership and maintenance cycles.
04Best & Worst Engines
Best Diesel Overall
635d (M57D30, 3.0-litre twin-turbo, 2007–2010)
“The 635d is the rarest and most surprising E64 engine — a 3.0-litre twin-turbo diesel with 286 bhp and 580 Nm of torque that transforms the convertible into a genuine continent-crushing grand tourer. It's the only E64 engine that delivers effortless torque and 40+ MPG economy. The M57 is one of BMW's most durable diesel engines.”
Who it's for: buyers who want the ultimate E64 cruiser with diesel economy.
Best Petrol Overall
N52B30 (3.0-litre straight-six, 630i, 2004–2007)
“The N52 is BMW's last naturally aspirated straight-six without direct injection — smooth, linear power delivery, and none of the N62's V8 complexity or the N53's high-pressure injector issues. It's the most reliable E64 engine and the one we recommend for daily use. The 258 bhp is plenty for a grand tourer.”
Who it's for: buyers who want straight-six refinement and proven reliability.
Highest Risk
N62B48B (4.8-litre V8, 650i, 2005–2010)
“The N62 V8 is a glorious engine — 367 bhp, 490 Nm of torque, and a soundtrack that defines the E64 experience. But it suffers from well-documented valve-stem-seal failure (blue smoke on startup), cooling system failures, alternator bracket gasket oil leaks, and PCV system issues. It's the most expensive non-M E64 engine to maintain.”
Who it's for: buyers who want V8 character and are prepared for V8 maintenance costs.
Most Expensive Failure
S85B50 (5.0-litre V10, M6, 2006–2010)
“The S85 V10 is one of BMW's most spectacular engines — 507 bhp, 8,250 rpm redline, and a sound that's pure motorsport. But it's also one of the most expensive to maintain: rod bearing wear is the defining failure, requiring an engine-out service at £3,000–£5,000. Throttle actuators, VANOS and SMG pumps are additional common failures. A full engine replacement can exceed £15,000. Only 5,000 E64 M6 convertibles were built.”
Who it's for: collectors with deep pockets who understand the S85's demands.
Best Value
630i (N52B30, pre-LCI)
“The 630i delivers 258 bhp, 300 Nm of torque, and genuine 30+ MPG economy in a grand tourer package. It's the lightest E64 engine, the most reliable, and the cheapest to maintain. It's the sensible choice that still delivers the E64 experience — just without the V8's running costs.”
Who it's for: buyers who want the E64 experience without the V8's fuel and maintenance bills.
Most Overlooked
635d (M57D30, twin-turbo diesel)
“The 635d is the rarest E64 engine — only produced from 2007 to 2010 and in limited numbers. It's often overlooked in favour of the V8s, but it delivers 286 bhp, 580 Nm of torque, and genuine 40+ MPG. It's the E64 for buyers who actually drive their cars.”
Who it's for: buyers who want the ultimate E64 GT car for long-distance touring.
Best Diesel Overall
635d
(M57D30, 3.0-litre twin-turbo, 2007–2010)
“The 635d is the rarest and most surprising E64 engine — a 3.0-litre twin-turbo diesel with 286 bhp and 580 Nm of torque that transforms the convertible into a genuine continent-crushing grand tourer. It's the only E64 engine that delivers effortless torque and 40+ MPG economy. The M57 is one of BMW's most durable diesel engines.”
Who it's for: buyers who want the ultimate E64 cruiser with diesel economy.
Best Petrol Overall
N52B30
(3.0-litre straight-six, 630i, 2004–2007)
“The N52 is BMW's last naturally aspirated straight-six without direct injection — smooth, linear power delivery, and none of the N62's V8 complexity or the N53's high-pressure injector issues. It's the most reliable E64 engine and the one we recommend for daily use. The 258 bhp is plenty for a grand tourer.”
Who it's for: buyers who want straight-six refinement and proven reliability.
Highest Risk
N62B48B
(4.8-litre V8, 650i, 2005–2010)
“The N62 V8 is a glorious engine — 367 bhp, 490 Nm of torque, and a soundtrack that defines the E64 experience. But it suffers from well-documented valve-stem-seal failure (blue smoke on startup), cooling system failures, alternator bracket gasket oil leaks, and PCV system issues. It's the most expensive non-M E64 engine to maintain.”
Who it's for: buyers who want V8 character and are prepared for V8 maintenance costs.
Most Expensive Failure
S85B50
(5.0-litre V10, M6, 2006–2010)
“The S85 V10 is one of BMW's most spectacular engines — 507 bhp, 8,250 rpm redline, and a sound that's pure motorsport. But it's also one of the most expensive to maintain: rod bearing wear is the defining failure, requiring an engine-out service at £3,000–£5,000. Throttle actuators, VANOS and SMG pumps are additional common failures. A full engine replacement can exceed £15,000. Only 5,000 E64 M6 convertibles were built.”
Who it's for: collectors with deep pockets who understand the S85's demands.
Best Value
630i
(N52B30, pre-LCI)
“The 630i delivers 258 bhp, 300 Nm of torque, and genuine 30+ MPG economy in a grand tourer package. It's the lightest E64 engine, the most reliable, and the cheapest to maintain. It's the sensible choice that still delivers the E64 experience — just without the V8's running costs.”
Who it's for: buyers who want the E64 experience without the V8's fuel and maintenance bills.
Most Overlooked
635d (M57D30, twin-turbo diesel)
“The 635d is the rarest E64 engine — only produced from 2007 to 2010 and in limited numbers. It's often overlooked in favour of the V8s, but it delivers 286 bhp, 580 Nm of torque, and genuine 40+ MPG. It's the E64 for buyers who actually drive their cars.”
Who it's for: buyers who want the ultimate E64 GT car for long-distance touring.
Engine
Typical Mileage
Common Major Failure
Repair Cost (Specialist)
Replacement Cost (Recon)
Ownership Verdict
Best Petrol -reliable, simple, no turbo worries
Watch -direct-injection complexity
Most Expensive Non-M -V8 complexityMost Expensive Non-M -more power, same issuesBest Diesel -bulletproof M57, rare in convertible
Enthusiast Only -spectacular but demandingEngineTypical MileageCommon Major FailureRepair Cost (Specialist)Replacement Cost (Recon)Ownership VerdictBest Petrol -reliable, simple, no turbo worriesWatch -direct-injection complexityMost Expensive Non-M -V8 complexityMost Expensive Non-M -more power, same issuesBest Diesel -bulletproof M57, rare in convertibleEnthusiast Only -spectacular but demanding
The E64 rule
A £6,500–£10,000 N62 recon against a £8,000–£20,000 E64 sits at 33–125% of the car's value. On a sub-£10,000 E64, that brushes our 70% BMW threshold -we'll honestly tell you to walk away. Against a well-kept £18,000+ example, the same recon drops to a routine 36–56% -a repair decision, not a financial one. Value the car first, and always check for valve-stem-seal smoke on V8 cars. The convertible roof mechanism also adds a unique cost dimension to E64 ownership.
Key Takeaways
Which E64 Costs Least To Own?
630i (N52, pre-LCI) -simple straight-six, reliable, cheap parts.
Which E64 Costs Most To Own?
M6 (S85 V10) -rod bearings, VANOS, throttle actuators; V10 running costs.
Which E64 Is Best Value?
630i (N52) -the most reliable E64 engine, the cheapest to run, and still a genuine grand tourer.
N62
V8 Valve Stem Seal Failure
Affected models:
E64 645Ci, 650i (N62B44 / N62B48, 2004–2010).
Typical failure mileage:
60,000–100,000 miles.
Root cause:
The N62 V8 suffers from valve stem seals that harden and lose their sealing ability over time. This allows oil to seep past the seals and into the combustion chamber, particularly when the car has been sitting overnight. The classic symptom is a puff of blue smoke on cold startup. Over time, oil consumption increases and catalytic converters can be damaged.
Tiered Cost Table
Dealer
Dealer
Specialist
Specialist
Dealer
Specialist
Our Recommendation
If your N62 V8 smokes on startup, budget for valve-stem-seal replacement immediately -a £1,500–£2,500 repair is dramatically cheaper than the £6,000+ replacement that follows if the catalytic converters are destroyed or the engine suffers further damage. Use high-quality oil and change it regularly to slow seal degradation.
N62
V8 Cooling System Failures
Affected models:
E64 645Ci, 650i (N62B44 / N62B48, 2004–2010).
Typical failure mileage:
60,000–100,000 miles.
Root cause:
The N62 V8's cooling system is a known weak point -the water pump, thermostat, expansion tank and plastic coolant pipes all age poorly. The engine's aluminium block is intolerant of overheating, and a failed cooling system can lead to catastrophic engine failure. The alternator bracket gasket is also prone to oil leaks, which can drip onto the exhaust and cause smoke.
Tiered Cost Table
Dealer
Dealer
Specialist
Specialist
Dealer
Specialist
Our Recommendation
If you own an N62 V8 E64, treat the cooling system as a consumable -replace the water pump, thermostat and expansion tank proactively at 80,000 miles. A £400–£900 preventative service is dramatically cheaper than the £6,000+ replacement that follows an overheat.
S85
V10 Rod Bearing Failure
Affected models:
E64 M6 (S85B50, 2006–2010).
Typical failure mileage:
40,000–80,000 miles.
Root cause:
The S85 V10 is notorious for rod bearing wear -the bearings can fail due to insufficient oil clearance from the factory, leading to catastrophic engine failure. The classic symptom is a metallic knocking sound from the bottom end, particularly when cold. This is the single most expensive failure on the E64 M6.
Tiered Cost Table
Dealer
Dealer
Specialist
Specialist
Dealer
Specialist
Our Recommendation
If you own an E64 M6, budget for rod bearing replacement as preventative maintenance at 50,000 miles -£2,500–£4,000 is dramatically cheaper than the £8,000+ replacement that follows if the bearings fail. Listen for any metallic knocking and use the correct 10W-60 oil.
E64
Convertible Roof Mechanism Issues
Affected models:
All E64 convertibles (2004–2010).
Typical failure mileage:
Not mileage-dependent -age and use-related.
Root cause:
The E64's fully automatic soft-top roof relies on a complex hydraulic system with multiple rams, pumps and sensors. Common issues include hydraulic fluid leaks, failing roof motors, sensor failures, and worn roof latches. The roof can become stuck partially open or fail to operate entirely.
Tiered Cost Table
Dealer
Dealer
Specialist
Specialist
Dealer
Specialist
Our Recommendation
Have the roof mechanism inspected regularly -a £200–£500 preventative service is dramatically cheaper than the £1,200+ repair that follows if the hydraulic system fails. Check for any hesitation or unusual noises when operating the roof.
VariantEngine Code
Used (Supply)
Reconditioned (Supply)
Rebuilt (Supply)
Labour HoursScope note: All variants listed are E64 convertible only -the two-door, four-seat convertible produced from 2004 to 2010. E63 Coupé shares most of these engines but is covered on its own Generation Page, as fitment and labour access vary slightly by body style. The 645Ci was produced only from 2004–2005 and replaced by the 650i from October 2005. The 635d was introduced with the 2007 LCI.
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
£2,500–£15,000
reconditioned, supply only
[BMW‑QUOTE]
Most Common Failures
Live FeedBMW 650i
E64
SurreyBlue smoke on startup, valve stem seals5
enquiries
Updated MonthlyBMW 630i
E64
BristolVANOS solenoid fault, check engine light3
enquiries
Updated MonthlyBMW M6
E64
OxfordshireMetallic knocking, suspected rod bearing wear2
enquiries
Updated MonthlyMost Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
£2,500–£15,000
reconditioned, supply only
[BMW‑QUOTE]
Most Common Failures
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
£2,500–£15,000
reconditioned, supply only
[BMW‑QUOTE]
Most Common Failures
Scope note: All variants listed are E64 convertible only -the two-door, four-seat convertible produced from 2004 to 2010. E63 Coupé shares most of these engines but is covered on its own Generation Page, as fitment and labour access vary slightly by body style. The 645Ci was produced only from 2004–2005 and replaced by the 650i from October 2005. The 635d was introduced with the 2007 LCI.
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
£2,500–£15,000
reconditioned, supply only
[BMW‑QUOTE]
Most Common Failures
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
£2,500–£15,000
reconditioned, supply only
[BMW‑QUOTE]
Most Common Failures
Most Requested Engines (2025)
Most Requested Variants
Average Replacement Cost
£2,500–£15,000
reconditioned, supply only
[BMW‑QUOTE]
Most Common Failures
Live FeedBMW 650i
E64
SurreyBlue smoke on startup, valve stem seals5
enquiries
BMW 630i
E64
BristolVANOS solenoid fault, check engine light3
enquiries
BMW M6
E64
OxfordshireMetallic knocking, suspected rod bearing wear2
enquiries
Updated MonthlyTrusted E64 Engine Suppliers
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