C'mon, the 190 series (W201) has been introduced after the R107. The original wonky numbering system is on the W111 between 1959 and 1968 with a single outlier in the "280 SE 3.5" instead of "350 SE" as you would expect from the other model numbers (220/230/250/280 all being roughly 1/10 of the displacement). Afterwards between 1965 and 1972 the W108/W109 series came which sometimes had 1/10th of it's displacement in the moniker, but sometimes "280 SE" or "300 SEL" with the displacement (3.5, 4.5 or 6.3) only added to the end...
Then again, the BMW E46 line was all over the place as well: 316i with 1.6, 1.8 or 1.9 litres, 318i with 1.9 or 2.0 litres, 320i with 2.0 or 2.2 litres, 323i and 325i with both 2.5 litres and 318d with two different 2.0 litre-engines...