Before you ask, no, neither car is mine.
The S500 (with an AMG sport package or something of the sort) belongs to my Grandmother. The Q45 is the property of my older cousin Julian.
Well, three days ago, my Grandmother and I switched cars (well, my car used to be hers anyway) as I needed space for 5 people and film equipment. Last night, as I was heading to her house to switch back, I noticed a car moving rather swiftly down the Bee-Line Highway (long, straight, dark, largely unpatrolled backroad highway that runs diagonally). At one of the few intersections, there was a red light and we ended up side by side. I look over, and it's my cousin in his Q.
We both wind down our windows, and before I can say anything, he, smiling broadly, just yells "You're going to lose". The light turned green, and both of us eased the cars (both autos) into speed. After gradually building up through first, I was flat through second and so on. The Q walked it though. I kept it on up to 110 and he slowly pulled away the entire time, had about 2-3 lengths on me when I shut down.
He lives in the same neighborhood as my Grandmother, so we drove together, with him taking every red light as an oppurunity to point and laugh.
We're going to meet-up soon though and I'll take my XK against him, although, even then, I'm not sure I'll win.