Normal phenomenon. The BMW 5 Series is one of BMW's flagship cars. The vibration of the vehicle's heater pipe is caused by the engine's excessive horsepower, which is a normal phenomenon. BMW (BMW), the Chinese full name is Bavaria Engine Manufacturing Co., Ltd., a German automobile brand. BMW's car series has 4 models i, X, Z, and pure numbers, 1, 2, 3, 4, 5, 6, and 7 , 8 and other series, as well as the M series (BMW's official high-performance modification department) which is improved on the basis of each series.