You may have 2 issues
1)failure to start - is it trying to crank? if not, the interlocks may not be happy. Steering wheel, brake pedal, gear selector interlocks ok?
2) power loss. Baring a major mechanical malfunction (not likely, you'd probably notice something so major...) it sounds like a sensor to me. Sorry but you may have to get at that cam sensor. Different car, but a co-worker had the exact same thing happen on his PT Cruiser, would start and kinda run, no codes. Cam sensor.
imho, Avoid Mini Cooper unless you are in the market for a depreciating, poorly made, problem ridden pile of $hit. FWIW we are really enjoying our 2013 Fiat Abarth.