Many Americans are not aware that six cylinder engines have been available most of the last 50 years in all senior Mercedes-Benz vehicles. After building straight eights and a few V12s in the 1930s, Mercedes literally bet the store on sixes for the 1950s. It was a mistake of course to believe that the best cars in the world could do with only six cylinders. More is better, right? Except for Ferrari, postwar manufacturers were quite satisfied with six cylinder engines in everything from racecars to very large trucks. Rolls Royce offered 4.5 and 4.9 liter sixes during the 1950s. The most famous SL of them all is “only” a six. Ditto Jaguar’s XK120, C and D-Type. And the Aston-Martins and Maseratis of the 1950s. Even Enzo Ferrari’s son persuaded his father to built V6’s in the 1950s. One argument is that a six has less cylinder wall surface than the same cubic inches of eight or twelve cylinders, therefore hosting less friction and more power.
Only a few American companies championed big sixes. Hudson’s Hornet, the darling of 1950s stock car racers, is a 5 liter six. Unlike Europe, the US government’s low tax on gasoline invited large cars and large engines. After retirement M-B’s most famous engineer, Rudolf Uhlenhaut, was asked by a journalist which Mercedes during his years was the most significant? Uhlenhaut’s reply was the 220 sixes; “they were the meat and potatoes cars that put us into black ink making happy clients worldwide.”
Initially, the “new” 1971 SL was introduced only as a 3.5 V8. There was an immediate outcry for a six especially in nations that tax cars by engine size. In 1974 the 2.8 liter twin-cam SL arrived and sixes have been offered ever since. 25,436 280SLs were sold during between 1974 and1984, plus another 13,742 with the 3.0 liter six of 1985/1989. But not so in the USA where MBUSA’s (then MBNA’s) success identifying and connecting with V8 clients kept the sixes off show room floors for 16 years. Some private importing occurred and there are a few 107 body sixes offered in every issue of SLML. The 320SL straight six was available in the US from 1990 into 1997 but was dropped only in the US in 1998, the same year the V6 SLK and SL debuted.