2009 Mercedes-Benz C-Class C300 Sport 4dr Sedan (3.0L 6cyl 6M)
I initially looked at the Mercedes because it is one of the few 6 cyl cars that are available in a manual transmission. I test drove the 328i sedan on the same day as the 300. My whole family liked the c 300 better for the ride and the sitting position/comfort. The 328 was an auto. It seemed like the engine of the 328 was straining and a bit noisier than the 300. Also, it was difficult to get a 328i without a bunch of add- ons. Same with the Infinity G-37 MT. It was difficult to find without so many options. The only options on my 300 are the burl walnut dash trim and the ipod adapter. So the list on my car was around $34,000.
Acceleration. Comfort. Smooth ride.
Get rid of the tire air pressure monitoring. That thing gives warnings sometimes 3-4 times during a 15 to 20 minute drive. A bit more leg room in the rear.