I was going to say that 250 is similar to the torque on the 250 (258lb), but that would be a bad guess.The E and S63 were called that because they originally had the M156 6.2L V8 which was the first AMG designed engine. The reason it was called a 6.3 is to pay homage to the M100, Mercedes' first V8. I assume when they come up with a brand new E and S they may change the numbering.
The other CLA numbers are reasonably related to displacement or something else (45 to AMG's anniversary), but the 250 I can't place anywhere.
So by that logic the marketing guy who came up with the Dodge Dart Swinger was wearing beer goggles and the Subaru Brat must've had a big fight with his teenage son. And the Ferrari LaFerrari and Renault LeCar guy must've been bored. Thank god Mercedes Jellinek wasn't named Bertha. Otherwise we'd all be drooling over the Bertha CLA. Imagine a Bertha with Kompressor on it.Picturing an engineer saying... "Let's call this car the 258!"
Then someone in marketing reads it with fuzzy glasses as 250... and the name was born.