In the past, you would know what is under the hood of the vehicle when you here the name of the model but that is no longer the case now as Mercedes seems to be naming their vehicles however they want.
The numbers used to mean the engine displacement in the past which means an S500 model will come with a 5.0-liter engine while the C63 would come with a 6.3-liter engine but that is not the case now.
While the number does not necessarily show you the engine displacement now, it still tells you if the which models has a bigger engine. If you are comparing g Mercedes models, you should know that the model with the higher number will come with a bigger engine.
Mercedes choosing to offer the same vehicle with a different model number based on the region has also made their buyers more confuses. Although most people probably won’t mind it since it is just a name but why make it so confusing?