A 720S is a $300,000+ car. The difference between a good purchase and a money pit is usually visible to someone who knows what to look for.
This checklist is what I would go through if I were buying another 720S. It covers the structural stuff that matters, the wear items that are expensive to fix, and the diagnostic checks that reveal hidden problems.
Mono-cell chassis: Look at the weld seams along the sills, A-pillars, and rear bulkhead. Factory welds are clean and consistent. Repair welds look different — rougher, with heat discoloration. If you see patch panels or bondo in structural areas, walk away.
Crash structure areas: Check the front crash cans behind the bumper and the rear impact structure. These are designed to crush in a collision and should show no deformation unless the car has been in an accident.
Panel gaps: Uneven panel gaps can indicate prior bodywork. On a McLaren, gaps should be consistent and tight. If the hood gap is 3mm on the driver side and 8mm on the passenger side, something was realigned.
Control arm bushings: Look for cracks, splits, or oil seepage. The front control arm bushings wear faster on cars that have been driven hard. Replace them before they fail — a broken bushing at speed is dangerous.
Trailing arms: Check the rear trailing arm mounts for cracks. These are aluminum and can develop stress fractures, especially on high-mileage examples.
Damper condition: Look for oil leaks around the PCC damper bodies. Small seepage is normal; active dripping means the dampers need replacement, which is a $4,000+ job all four corners.
Sway bar links: Shake the front end (with the car safely lifted). Play in the sway bar end links is common and inexpensive to fix, but it tells you how roughly the car has been driven.
Pad thickness: Minimum safe thickness is 3mm of friction material. If any corner is at or below that, factor pad (and possibly rotor) replacement into your purchase price.
Rotor condition: Look for deep grooving, hot spots (blue discoloration), or cracking. McLaren rotors are expensive — front big brake rotors run $800+ each.
Caliper operation: After a test drive, check that all four calipers released properly. Stuck calipers cause uneven pad wear and can drag a rotor to destruction.
Oil consumption: Ask the seller for oil top-off records. The M840T should consume less than 0.5 quart between 7,500-mile oil changes. More than that suggests worn piston rings or valve seals.
Cold start: Listen for excessive ticking on cold start. Some tick is normal (injectors, lifters), but loud knocking means a problem. Also check for blue smoke from the exhaust — that indicates burning oil.
Turbo inspection: Look at the turbo inlet hoses for oil accumulation. Excessive oil in the intake tract suggests turbo seal wear. Spin the turbo shafts (with the intake disconnected) — they should rotate freely without grinding.
Belt condition: Check the timing belt through the inspection port. Look for cracks, glazing, or missing teeth. Belt replacement is a major job — if it has not been done and the car is over 60,000 miles, budget for it.
This is where you separate serious buyers from tire kickers. Bring MDS (or hire someone who has it) and run a full module scan:
Seat condition: Check the bolster stitching for separation. McLaren seats take a beating and reupholstery is expensive. Also test all electric adjustments — stuck motors are a pain to fix.
Infotainment: Test every function: navigation, Bluetooth pairing, Apple CarPlay/Android Auto, climate control display, rear camera. The infotainment system is the most common failure point on 720S cars and replacement is costly.
Steering wheel wear: Heavy wear at the 9 and 3 o'clock positions indicates aggressive driving. Not a mechanical issue, but it tells you how the car was treated.
Before you even look at the car, ask for:
If the seller cannot provide basic documentation, that is a data point. Not necessarily a deal-breaker, but it means you need to be more thorough with the inspection.
This checklist covers the major items. The SIS browser has detailed inspection procedures for every system if you want to go deeper. And if you find something you do not understand, ask — I am happy to help interpret what you are seeing.