The XJR should have all of the XJ's luxury and charm, plus a healthy dose of aggressive style inside and out courtesy of the R badge.
Of course, the 550-horsepower supercharged V-8 engine under the hood won't hurt anything.
Almost certainly the same engine in essentially the same tune as found in the XFR-S, the 5.0-liter force-fed V-8 should get the big XJR to 60 mph in well under 5 seconds--perhaps even closer to the mid-4s. Top speed will likely be limited to 186 mph or so.
An eight-speed paddle-shifted ZF automatic transmission is almost a given, as is rear-wheel drive, naturally.
Expect a retuned suspension, wider wheels and tires, and more powerful brakes, too.
The full details will come early next week at the New York Auto Show.