One thing you'll quickly notice about driving through Madrid and the Basque country of northern Spain – it's a helluva lot quieter than Los Angeles. Echoes of cranked sound systems, blaring aftermarket exhaust pipes, incessantly blaring horns, and the general hum of too many noxious gas producing vehicles in too tight a confine are blessedly absent. Instead, the bustling streets and narrow, winding back roads play host to surprisingly quiet diesels en masse, with more of the relatively small rides fitting on each square inch of asphalt.

That serenity was soon transformed by the thunderous song of a fleet of 2007 Jaguar XKRs. Out of the city and en route, we abided by the road signs directing us to slow to 50 or 70 kph, the XKR's exhaust settling into a quiet, subdued tone that allowed the curious townspeople, those not shut in during the afternoon's extended siesta, to appreciate the grace and style of Jaguar's ultimate sports car. Kids cheered, elderly ladies smiled and waved, and men of all ages appeared a bit dumbfounded in this land of well-used Opels and Citroens. However, marking the villages' exits were often signs reading 90 or 100 kph, at which time we hammered down the XKR's well-modulated throttle. The exhaust opened up wide and alerted everyone within earshot that the town's brief visitor was hell bent on reaching maximum velocity.

With a 0-60 mph acceleration time of only 4.9 seconds in coupe trim, one might imagine some mild neck-snapping upon wide-open takeoff, though that's not the case. Jaguar engineers claim their goal was to marry outright performance with some semblance of refinement, luxury, and control. The result is impressive launch speed, albeit not amazing. Find a flat stretch of isolated roadway, turn off the traction/stability control, and a hard jump on the throttle will unleash solid acceleration, though there will be no rubber marks on the road to signify the event. Instead, the heart of the supercharged V8's power lies in the mid range, a point where the driver will find an unyielding ability to rocket from high speeds to rates those puny little Spanish police cars couldn't even dream of matching. On numerous occasions, we saw the speedometer, set at a comfortable 170 kph, effortlessly jump to 210 and beyond. It felt like 105 kph in your average sport coupe, with the suspension hunkering down and providing the perfect blend of comfort and stability. Except for some wind noise and tire noise, the cabin remained quiet in the coupe, and nearly as much so in the convertible.

Strolling slowly between historic cobblestone buildings, the XKR's suspension made for a stiff ride, though the sport bucket seats were extremely supportive and the Servotronic steering required little effort at such slow speeds. Visibility was a trick in convertibles and coupes because of wide rear pillars and small rear windows. Venture out into the twisties only to unleash a chassis that remains utterly flat during hard cornering, Dunlop SP Sport Maxx tires hungering for abuse, and responsive brakes that certainly smell hot under duress but never show signs of fade. If there's an area needing improvement, it might be the steering – even though it has been tuned for use in the XKR, the system feels lighter than expected in such a capable machine.

That leaves one point for discussion – the exquisite six-speed automatic transmission. In normal mode, shifts are smooth, with hard dumps of the throttle resulting in aggressive downshifts. Click the tranny into sport mode and, as expected, the 420 horses feel more eager to let loose and revs are held longer and higher before upshifts. Furthermore, the transmission recognizes driving styles, gradients, and speeds, allowing it to react appropriately, such as blipping the throttle and downshifting as the driver heads downhill into a curve. And then there are the paddles (downshift on the left, upshift on the right), which Jaguar claims change gears in fewer than 600 milliseconds – we didn't pull out the stopwatch, but the only time we felt a bit of delay was when trying to downshift before the XKR agreed we were in the proper rev range.