Which are the two most common types of suspension systems in use today?

The two most common types of suspension systems in use today are indeed leaf spring and coil spring systems. Leaf springs have been widely used in vehicles for many years, especially in trucks and heavier vehicles, providing a robust solution for load-bearing applications due to their ability to distribute weight over a larger area. On the other hand, coil springs are prevalent in automobiles and offer a smoother ride by absorbing shocks more effectively. They are often used in conjunction with shock absorbers to enhance ride quality and improve handling.

While other options might include components or systems related to suspension, they do not represent the mainstream solutions commonly found in vehicles today. Air springs, for instance, are used in specific applications for their adjustable ride height but are not as universally applied as leaf and coil springs. Static and dynamic springs refer to principles of spring function rather than specific types of suspension systems and thus do not represent common suspension designs.