Our 2007 XKR Coupe fully lived up to the old Jag slogan "grace, space and pace," with a lithe body packed full of luxury and a bonnet stuffed with a 4.2-liter, 420-horsepower, supercharged V8. Thanks to its six-speed automatic transmission--locked into sport mode, of course--and some judicious handling of the steering wheel-mounted paddle shifters, it was even more fun than …