Fuel Injector problems of the 2011 BMW X5

Engine stalled while driving. Warning lamps indicated reduced power. Several occurences were at speed on the interstate. Car would restart after sitting for several hours. Car was left with BMW for service. However, BMW said they could not replicate the problem and did not perform any repairs the first time. Car again died while driving at speed on highway several weeks later. BMW stated that there was loss of engine compression. Then, stated that fuel injectors were faulty. Then, claimed that it was due to "bad gas" and/or sugar in the gas tank.