Thanks for all of the replies!

When it just sits idling on the driveway and I rev it up to say around 4k rpm, it emits intermitent low-volume gurgling noises from the exhaust (rear) after I release the accelerator. I'm wondering if this is normal, too.

My Toyotas don't do that and this is the first Mercedes-based product I've ever owned. I love the car, though. This new corvette pulled behind me going down a straight-away today, on my bumper to see what I would/could do. I depressed the accelertator half-way and left him in the the distance. I was going 100 before I knew it. He didn't follow me after that.