Even though the 2007 Jaguar XK’s engine is more powerful and the transmission is improved, the most notable change to the new XK is the actual body of the car. The all-aluminum unibody, the manufacture of which is largely accomplished via bonding and riveting techniques, is lighter and stiffer than the previous XK8 – and the competition, according to Jaguar. What’s new to the XK isn’t necessarily new to Jaguar, however, as much of the underpinnings are shared with the Jaguar XJ sedan. The technology is new to this Jaguar, however, and a quick glance at curb weight specs across the luxury sports coupe/convertible class bears out the benefits.