McLaren 720S Reliability: The M840T Daily Reality
Common Failure Points & Costs
| Component | Failure Mileage | Symptom | Est. Cost (USD) | Risk Level |
|---|---|---|---|---|
| Hydraulic Suspension System (HRLS) | 20k - 50k miles | Hydraulic fluid beneath the car, suspension inconsistency, stranded risk | $3,000 - $8,000 | Critical |
| Engine Belt Drive | Service interval dependent | No warning before catastrophic failure — follow schedule | $2,000 - $4,000 (service) / $15,000+ (failure) | Critical |
| Proactive Clutch (MCT) | 30k+ miles (track) / 60k+ miles (street) | Jerky at low speed, slipping, hesitant engagement | $5,000 - $12,000 | High |
| Coolant Hoses | 40k - 60k miles | Coolant loss, overheating | $800 - $2,000 | High |
Reliability Verdict
The 720S is the most accessible of the M840T platforms and the most widely understood. Its key ownership risk is the hydraulic suspension system — the most-discussed expensive repair in 720S forums. Engine reliability is generally strong when serviced correctly. The belt drive and MCT are predictable costs; ignoring them is the path to four-figure repair bills.
McLaren 720S Reliability: What £270,000 Gets You at Year 5
The McLaren 720S (2017–2021) is the car that made McLaren a serious force in the supercar market. At 710 hp from a 4.0L twin-turbo V8, 0–60 in 2.8 seconds, and a carbon fiber monocoque, it outperforms nearly everything at its price point on a racetrack.
Off the track, it is one of the most demanding cars to own in the used supercar market.
1. The 720S in the Used Market
The 720S launched at approximately $285,000 (US) and is now available used in the $150,000–$220,000 range depending on mileage and specification. This price point brings it within reach of buyers who have never previously owned a McLaren.
That transition from traditional luxury to supercar ownership is where most financial surprises happen.
2. The Hydraulic Suspension: Your First Expensive Repair
The 720S uses the same Hydraulic Reactive Load Control (HRLS) suspension as all Sport Series McLarens.
The system uses hydraulic pressure to control body motion in ways traditional suspension cannot. The result is extraordinary body control that transforms the car’s dynamics.
The trade-off: the system has multiple sealing points that age.
Key Facts
- First signs: Pink/reddish fluid beneath the car (hydraulic fluid, not oil or coolant)
- Failure mode: Gradual loss of hydraulic pressure → suspension behavior becomes inconsistent → eventually undriveable
- Mileage: Varies widely, 20,000–50,000 miles but age-related as much as mileage-related
- Cost: $3,000–$8,000 for hose/reservoir replacement
[!IMPORTANT] Always inspect the underside of any used 720S carefully before purchase. Any traces of pink or amber fluid are a hydraulic system issue that must be investigated.
3. Engine Belt: The Non-Negotiable
The M840T’s engine belt drive must be serviced at the manufacturer interval without exception. This is not the kind of service you extend beyond schedule:
- Service cost: ~$2,000–$4,000
- Failure consequence: Catastrophic engine damage — $15,000–$25,000+ repair
- Pre-purchase check: Any seller who cannot confirm belt service history gets a purchase price reduction equal to the service cost
4. MCT (Proactive Control Transmission)
The 720S uses McLaren’s 7-speed Seamless Shift Gearbox (SSG), also called the MCT/Proactive clutch system. Unlike a conventional DCT:
- Track use: Clutch wear accelerates dramatically under repeated high-G launches
- Street use: Change-quality issues begin appearing around 60,000+ miles
- Service: Fluid change every 20,000 miles (often ignored)
- Replacement: $5,000–$12,000 for clutch pack service
Recommendation: Verify transmission fluid service history. Extended intervals cause thermal degradation that accelerates clutch wear.
5. Year-by-Year 720S Reliability
| Year | Rating | Key Notes |
|---|---|---|
| 2017 | Fair | First year; best avoided unless full inspection |
| 2018 | Good | Software and calibration matured |
| 2019 | Good | Best early-production value |
| 2020 | Good | Performance Pack availability, solid build |
| 2021 | Very Good | Pre-facelift final year; well-understood used market car |
Best buy year: 2019–2020. Software mature, parts available, mileage typically manageable.
6. Real Annual Ownership Budget
| Item | Annual Cost |
|---|---|
| Annual service | $1,500 – $3,000 |
| Tires (Pirelli P Zero Corsa equivalent) | $2,500 – $4,000 |
| Hydraulic system reserve | $1,500 – $2,500 |
| Belt service (amortized) | $600 – $1,000 |
| Transmission fluid (amortized) | $400 – $800 |
| Annual Total | $6,500 – $11,500 |
This excludes any major engine-out event or track damage.
7. Buying Checklist
- Fluid inspection: Look under the car — any pink fluid = hydraulic issue
- Belt history: If unconfirmed, deduct full service cost from offer
- Track history: A 720S with lap history has significantly higher component wear rates
- Oil change intervals: Check for regular sub-6,000-mile changes
- MCT: Ask about transmission fluid history
Related Resources
- McLaren M840T Engine Reliability Guide
- McLaren 765LT Reliability Guide
- McLaren GT Reliability Guide
- Dual Clutch Transmission Problems
Expert Buying Advice
Inspect the underside for hydraulic fluid traces (pinkish fluid, distinct from oil). Confirm belt service history. Budget $7,000–$12,000/year for post-warranty costs. A 720S with a complete McLaren service history is worth a premium over one with service gaps.