This paper provides a synthesis of the information available describing the braking performance of heavy (on-highway) vehicles in the U.S. and contrasts the braking performance of heavy vehicles with that of passenger cars. It discusses the unique demands that are placed on heavy vehicle brake systems and shows that it is difficult to optimize braking performance for all operating conditions without adding complexity to the system. As designed, U.S. heavy-vehicles do not perform as well as cars. In addition, heavy vehicle brake performance can degrade significantly from the design-intent level if proper maintenance is not performed. The brake maintenance situation in the U.S. leaves something to be desired.