Re: High end speed
ALL cars sold in Germany are limited by the manufacturers to 155. This is by an agreement between manufacturers rather than by law. Of course, there are ways to defeat this function and apparently many buyers do this.
According to the test reports I have read, the SRT6 has a speed limiter set to 158. The regular NA XF does not have a speed limiter, but will hit its engine's rev limiter (ca. 6,200 rpm) at right around 150 mph.
Please note that the Crossfire is not particularly aerodynamic. While it has a relatively small frontal area, the cD -- coefficient of drag -- is a relatively high 0.39. By contrast, the current M-B C Klasse sedan has a fine cD of 0.29. Most current road cars claim a cD in the low-to-mid 0.3xx range. The lowest claim I've ever read for a real world road car is 0.27 (perhaps the Honda Insight?). The lowest claims I've seen for ultra-high efficiency prototypes was around 0.14, for cars with skirted front and rear wheels running extremely narrow high-pressure tires, all completely impractical in world of real roads.