Automobile classification standards are divided according to wheelbase, displacement, weight and so on:
Class A: Small cars with a wheelbase of 2.3m to 2.5m, such as Audi A 1.
Class B: Intermediate cars with a wheelbase of about 2.5m to 2.8m, such as Audi A4.
Class C: medium and large-sized vehicles with a wheelbase of about 2.8m to 3m, such as Audi A6L.
D-class: luxury car, the wheelbase is generally more than 3m, and the displacement is basically above 3.0l, such as Audi A8L.
Nowadays, the wheelbase of automobiles is lengthened, especially after entering China. In order to cater to China people's preference for large space, Audi A6L is an extended version with a wheelbase of 30 12mm, which belongs to the category of C-class cars.