McLaren 720S (M840T): Reliability Guide & Ownership Realities
"Before you commit to the McLaren 720S, you need to understand its complete reliability profile Ethe good, the bad, and the potentially catastrophic. This data-driven guide gives you the full picture."
Engine
6/10
Gearbox
6/10
Electric
5/10
Total Risk
5/10
Quick Verdict
Buy with WarrantyUnmatched hypercar performance, but plagued by fragile PCCII hydraulic suspension accumulators and electronic gremlins.
Reliability Verdict
The 720S is a hypercar-killer that requires hypercar-level maintenance. The engine is robust but the chassis systems (PCCII) and glass components suffer from 'teething' issues that McLaren has addressed in later revisions. Expect one $5k repair per year beyond standard maintenance.
Executive Intelligence Summary
McLaren 720S real ownership costs: PCCII suspension accumulator failure ($4,500), stress-crack windshields ($7,000), turbo oil line fire risk, and honest verdict E is the 720S worth it without warranty?
In This Guide
McLaren 720S Reliability: Performance vs. Fragility
The McLaren 720S redefined what a supercar could do. With 710 horsepower (officially—any dyno higher) and a carbon-fiber Monocage II, it remains one of the fastest road-legal vehicles ever produced.
However, McLaren’s reputation for build quality varies wildly. To own a 720S out of warranty is an act of bravery that requires a deep understanding of the car’s peculiar failure modes.
Failure Probability Timeline
Infancy period where assembly issues usually manifest.
- Windshield stress cracks
- Misaligned door seals
- Software gremlins
The component wear phase for the sophisticated hydraulic suspension.
- Suspension accumulator failure
- Coolant hose clamp leaks
- Turbocharger speed sensor fault
Long-term thermal degradation starts affecting high-heat zones.
- Turbo oil feed line weepage
- Engine mount settling
- Ignition coil pack burnout
*Data based on owner-reported failures and specialist shop frequency reports.
1. The PCCII System: Hydraulic Magic and Its Cost
Unlike Ferraris or Lamborghinis, the 720S does not use traditional anti-roll bars. Instead, it uses ProActive Chassis Control II (PCCII), a complex network of hydraulic lines and accumulators that cross-link the dampers.
The Accumulator Failure
The nitrogen-filled accumulators (there are four main ones) eventually lose their charge or the diaphragm fails.
- The Symptom: The car’s normally supple ride becomes harsh, bouncy, and jittery. You may see a “Suspension Fault - Limp Home” message.
- The Fix: Replace all four accumulators.
- Cost: $2,500 - $4,500 at a specialist.
2. Engineering Dossier: The M840T Engine
The 4.0L Twin-Turbo V8 is a development of the earlier 3.8L unit. It is remarkably strong and capable of supporting 900+ hp with minor modifications, but it has “external” issues:
- Coolant Hose Leaks: McLaren famously used “one-time use” clamps that can lose tension. The fix is to replace them with constant-tension units, but the labor is high because the engine is buried deep in the chassis.
- Turbo Speed Sensors: Heat soak can kill the sensors that monitor turbo RPM. While the sensor is cheap, the labor is not.
3. Glass & Body: The Fragility Factor
The 720S uses thin-ply glass and a complex roof structure to save weight.
- Stress Cracks: Many owners have reported the windshield or the upper “gorilla glass” sections of the doors cracking for no apparent reason while the car is parked or driven over a bump.
- Repair: These are not simple glass swaps. They often require McLaren-certified technicians to ensure structural integrity is maintained.
- Cost: $5,000 - $7,000 per pane.
4. Ownership Reality: The McLaren “Tax”
Maintaining a 720S requires specialized diagnostic equipment (MDS). Independent shops are becoming more common, but they are still rare compared to Porsche or BMW specialists.
| Service | Cost (Specialist) | Cost (McLaren Dealer) |
|---|---|---|
| Annual Service (Oil/Filters) | $1,200 | $2,500 |
| Brake Flush | $400 | $800 |
| Spark Plugs (4-Year) | $1,800 | $3,500 |
| Accumulator Refresh | $2,800 | $5,000 |
5. Conclusion: Should You Buy a 720S?
The 720S is for the driver who prioritizes performance above all else. It is faster than an Aventador and more engaging than an F8 Tributo.
The Golden Rule: Never buy a McLaren without a Warranty or a $15,000 Slush Fund. If you have both, it is a life-changing machine.
Related Authority Guides
- McLaren 570S Reliability: The ‘Entry’ Level Risks
- McLaren GT Reliability & Real Costs
- Ferrari 488 vs. McLaren 720S: Maintenance Comparison
The Reality Layer: What Owners Underestimate
Buying McLaren 720S is often driven by emotion, but keeping it on the road requires cold, hard logic. The dealership service center will not volunteer this information, but specialist independent mechanics know the truth:
- The Component Labor Trap: Engineering density means simple parts (sensors, plastic coolant fittings) require days of labor to reach. A $50 part often results in a $3,000 labor bill.
- The “Lifetime Fluid” Myth: Manufacturers claim transmissions and differentials use “lifetime” fluids to keep estimated maintenance costs artificially low for the first owner. To avoid a $10,000+ rebuild, you must change these fluids every 40,000 miles.
- Cascading Failures: When an air suspension strut leaks, the compressor burns out trying to keep the car level. Ignoring a warning light for 48 hours on a McLaren can easily double the final repair invoice.
Caution
The Worst-Case Scenario: If you suffer a catastrophic failure without a comprehensive warranty or a dedicated $10,000+ emergency repair fund, you will be forced to sell the vehicle mechanically totaled at a massive loss.
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The Final Decision: Worth It?
Worth it if:
- You have a trusted, brand-specialized independent mechanic.
- You maintain a strict $5,000-$10,000 liquid repair reserve.
- You value the driving experience over strict financial rationality.
Not worth it if:
- You are stretching your budget just to afford the purchase price.
- You rely exclusively on the dealership network for out-of-warranty maintenance.
- You expect Toyota-like reliability and predictable ownership costs.
Related Intelligence
Executive Buying Advice
Look for 2019+ models where initial assembly quality improved. Verify if the suspension accumulators have been replaced with the updated part numbers. A McLaren Qualification Inspection (MQI) is mandatory.
