The Mini Cooper was first sold in the USA in 2002. Every MINI Cooper sold came with a great warranty that included normal tune-ups for the first 3 years. While the tune-ups were slightly different based on models it is critical to have the tune up done not just to maintain the warranty but more importantly to maintain the life of the car. The factory specs (MINI Cooper List of Service) have proven to be optimistic from an interval stand point and history has shown that more frequent routine work can delay major work for some time. It is cheaper to maintain it then it is to replace it. And special note should be taken that a dealer can NOT refuse a warranty when the maintenance is done by someone else.
The MINI Cooper is a very sophisticated car and the engine shares the same complexity. BUT routine tune-up maintenance can indeed be very easily done by almost everyone with ease. The first level of tune up simply consists of changing a few filters and new engine oil. If the car has any real miles on it you would be wise to also renew the belts and perhaps even hoses and brake pads. The most important thing you can do is to visually inspect everything and just as important feel the car as you drive it daily- in most cases the car will tell you when it needs attention. Things like radiator expansion tanks that crack, timing chains that rattle, or power steering pumps that leak or a clutch that slowly starts to slip, or Transmission problem all can be felt as you drive. It is a great ride for sure- pay attention and enjoy it.