BMW (sheer driving...displeasure)

We bought a five door F21 (118i) 2013 demo model with 5000 odd km. The main reason for upgrading from the e87 (120i) was because we needed 5 door which the e87 wasn't, our daugher was being born the day before. A couple of months after buying it, the car started jerking and losing power and a 'drive train' warning light came on. I discovered that many drivers have had this exact same \drive train"issue with the F21. A driver in Mexico was told by he's local dealer that it might be the fuel he is using that is causing the problem. I laughed it off"