I have a 2002 C320, and I've noticed that, at an idle, the engine almost makes a diesel-like growling noise. It's not nearly as loud as a diesel engine, but it's noticeable--even with the windows up. It's been bugging me some, but the car runs great. I only use premium gas, and it's not like I'm hearing knocks...it's just more of a feature of the engine's running.

Anyway, last night, I was sitting at an outdoor restaurant and the valet pulled up a brand new SL500 (beautiful), and I noticed that it's engine made the same noise as mine...I was sitting 15 feet away from it, and I could clearly hear it.

Is this just a thing with Mercedes engines? Has anyone else noticed this with the their cars? Any explanations?

Just curious.

Brian