With a design nearing six years old, Jag's Ian Callum-penned XK may be long in the tooth. But it's unquestionably one of the sexiest cars on the road, and the British brand has continuously sharpened this grand tourer's fangs with performance, handling, and suspension upgrades that have turned this Sunday driver into a track-day terror.

The latest iteration is a ragtop version of the XKR-S, a brute whose hard-edged character is made all the more visceral and apparent in the open air. Since the XK was originally designed as a convertible, the topless XKR-S doesn't suffer from any weird back-end bloat necessitated by additional bracing, and, underneath its cut-and-slit skin, it's fundamentally the same 550-horsepower machine as its lively sister coupe.

On a blustery spring test drive in New York, we found the XKR-S to feel remarkably alive from behind the wheel. It demands attention. Depress the pedal off of a stoplight, or an on-ramp, and you feel the flood of torque (502 lb-ft) hit the rear wheels, forcing them to spin ever so slightly before the traction control kicks in. The six-speed automatic transmission is faultless, summoning up the supercharged 5-liter V8's vociferous rip and snarl. In the rearview mirrors, traffic shrinks as the car's high, wide haunches remain ever-present. Oddly, even with the top down, the car's aerodynamics are such that your hair barely gets tousled, even at high speeds.

Sound inviting? Grab a spot in line and wait a year. Jag only built 25 for the U.S. market in 2012, and, even at $138,000 a pop, they've all been spoken for. [Jaguar.com]