Gen 1 MINI Cooper S - R50 or R53?

Over the last two weeks or so I have spoken with three people who have been looking for parts for their R50 Cooper S.  The first generation of BMW MINI Cooper S was (and is) the R53.  But there are cars out there with ID plates - I suspect that they are Aussie compliance plates rather than factory build plates - which identify them as R50 cars.  More intriguingly, I've heard of early and late cars identifying themselves as R50's when they are R53's.

Now, I'm a car geek and a bit of an automotive nerd.  And I kind of have to be if I am to have any chance of being able to help people choose the right parts for their car.  I really don't want to argue with customers 'cause that's no way to win people over but sometimes conversations just get off on the wrong footing, and from that point it's hard to pull them back.  More importantly, it matters because a Cooper S will use different brake, clutch and some engine components.

If your car claims to be an R50 and it has a supercharger and a six speed gearbox, it's a Cooper S, and it's an R53.  Beyond that, your car's serial number (the last seven characters of the VIN, which consists of two letters followed by five digits) will always provide an unambiguous identification of whether the car is an R50 or an R53.

Maybe MINI got it right with the second generation of cars after all - the second generation cars (well, the hatchbacks, anyway) have model number R56 for "justa" and Cooper S cars alike.