Well you have to consider that 99% of these cars still have only their delivery miles, or least, not very much more. They hardly get driven and when they do, it's only for a short while. (In fact, one recently set on fire because it had been left sitting for six months and probably not properly maintained). I'd wager also that there aren't many tire and brake manufacturers that make the exact size the F1 requires, and as such most will have their original tires and brakes.
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By now if any still had there original tyres then they would be dangerous to drive as the tyres life is finite (5-7 years is normally the max) and should always be printed on the sidewall, expect to see this brought in for MOT's within the next couple of years and the sizes themselves aren't that special anymore, the speed rating may be be trickier but i would be very very surprised if the tyres you could get today for the mclaren would be worse then any other supercars as they come from the same makers and made from the same compound.
Same with brakes, its not the shape its the compound, you can have discs made to order from anything you want, there's a company 3 miles from me who will make you a set of ceramics if you can provide the size or a template again the pad manufactures will still make to order and will simply apply there most modern compound just like any other car made.
As for the other points you made then fair enough i cant debate on those, except that the car was designed to be downforce neutral, it does however use assisted ground effect this made the motoring news back when the car was released and produced many articles barely any more intelligent the 'mclaren f1 has no downforce lol lol !!!! lol' something that has sadly stuck with the car and is remembered more as a design flaw then the feature it actually was.
Its also worth noting that even the downforce neutral model doesnt perform to badly at all on the grip tests.
(shamelessly stolen from wiki)
Cornering
* When performing the lateral acceleration exercise around a 200 ft (61 m) skidpad (for testing some aspects of cornering performance), the standard F1 machine achieves 0.86 G; compared to 0.99 G for the Saleen S7, 1.01 G for the Ferrari Enzo and 1.15 G for the Koenigsegg CC (all post year 2000 vehicles).[14][27]
* The standard F1 can perform the slalom exercise at 64.5 miles per hour (103.8 km/h).[27]
Braking
* The standard McLaren F1 performs the 60-0 mph brake exercise in 2.8 seconds, coming to a full halt in 127 ft (39 m), compared to 125 ft (38 m) for the Saleen S7, 109 ft (33 m) for the Ferrari Enzo and 105 ft (32 m) for the Koenigsegg CC (all post year 2000 vehicles)
If anyone has any figures for the winged versions i would be very grateful.
