These are easily recognized by their "round" bodies. Among old timers they are sometimes dubbed Mr. Magoo cars. They came in both small body and larger body versions but they all had single round headlights and were distinctly rounded all all body panels.
Introduced in 1955 these were Mercedes first uni-bodied cars and also the first delivered to the U.S in large numbers. The smaller models were only available as a four door sedan powered by four cylinder gas or diesel engines. The larger S class models were available with sedan, coupe and cabriolet bodies and all were powered by a six cylinder gasoline engine. An SE designation means that the engine is fuel injected. The 190SL falls into this category although many do not like to refer to it as a "Ponton."