The banks of cylinders are arranged in a horizontal formation that makes the engine flat. It provides a very low center of gravity and an aerodynamic profile. Most engines in road cars today come in two configurations. The V has two banks of cylinders arranged in a V shaped engine block. This is the most common configuration for six, eight, ten and twelve cylinders engines. Hence, the references to V-6, V-8, V-10 and V-12 cylinder engines. Another common configuration is the in-line configuration. The cylinders are arranged in a single row in the engine block and is most common with 4 and 6 (older) cylinder engines. Also sometimes called a flat 4, 6, 8, 10 or 12.