3 stands for BMW's customized car series number, and 25 stands for the engine displacement of the car, which is equal to or similar to the displacement. For example, the displacement of 325i is 2.5 liters, but the displacement of 520i is actually 2.2 liters. I means that the engine of the car is gasoline injection type, and if it is diesel engine, D is used. If you add a capital L before I, it means the wheelbase is longer. At present, all BMW 7 Series cars imported from China have L, such as 745Li.