My brother bought a 2003 mini cooper s two days ago and when we went to go do some spirited driving around town we found that when he was accelerating, the car cut out all power around 5000-5500 rpms and the service engine soon light came on, the car also will not drive or anything after that until we came to a complete stop turned the key off and then back on again(service engine soon light turns off after the car is restarted) also the car feels slower than i thought it should but that might be cause my brother was driving like a pus. also the car drives perfectly fine otherwise

 

Going to move you to the Stock Problems/Issues area.

So only the CEL light came on and not the EML that is in the center speedo? When either light come on you will have codes issued and in order to point you in the correct direction we need to know what those codes are. If you cannot get your hands on a OSB2 reader, suggest you take the car to an Autoparts store as unlike a dealer, they will usually read the code for free.