C250 / C220 engine noise

[steve-V8s]

Some C250 reviews comment that the engine is a bit “Gruff”or even noisy. Have driven a C220 and didn’t think it was that loud compared to my current BMW oil burner, it is definitely not as smooth but the Beemer is 6 cylinder and the Merc is 4 so not a surprise. Not driven a 250 yet, is the C250 louder than the C220? can’t think why it would be because as I understand it the engine is the same.