I have the 2005 Cadillac CTS Luxury Sport model w/navigation, and 5-speed automatic transmission. I actually bought my car used, (not a demo) w/4,100 miles. It is a blast to drive. My first choice had been a Chrysler 300C, but I had a Cadillac STS prior, and this to me drove so much better. The doors close solidly, and the fit and finish suprised me. This car is much quieter (wind noise) than my STS was. I highly reccommend it.
The navigation system, the Stabilitrak, and the handling.