Its big torque numbers aside, the engine is very thrilling when it comes on strong at higher revs, all the way to redline at 6500 rpm. Once, when we floored it in second gear, we had to ask ourselves, "Where's the torque?" because the car didn't accelerate quickly. The torque is mostly up there at 4400 rpm. The transmission was in manual mode, and it didn't kick down because we hadn't shifted it. One especially pleasant feature is that the manual mode (called Driver Shift Control) for the new five-speed automatic transmission is true, and doesn't override the driver; again, this is refreshing and unlike German thought. When the electronic transmission is left to its own algorithmic designs, it sometimes shifts back and forth in the leisurely 40-mph range.

In the handling department, the XLR was halfway home when it was mounted on the superb Corvette chassis, which is very strong and light; in fact, the XLR is assembled at the Corvette plant in Kentucky. New aluminum subframes were built to accommodate the XLR body, lengthening the wheelbase by one inch; along with the low stance, good weight distribution and lightweight aluminum suspension components, this edges the car in the direction of great handling. The XLR has a longer wheelbase and wider track than the SL500, SC430 and XK8.

The electronic active suspension is unique, and works exceptionally well. It's rocket science: Like the Corvette, it uses transversely mounted composite leaf springs front and rear with wishbone control arms. The monotube shock absorbers contain fluid with magnetic particles whose alignment controls the stiffness. Sensors read the road 1000 times per second and vary those magnetic fields.

In short, the XLR offers tenacious grip and excellent handling. It charges down rippled curvy roads and takes smooth sweepers flat out. If there are any hard edges to the ride we haven't felt them. It feels big, somewhat like the Corvette, but tighter, fast and quick.

The Michelin Z-rated run-flat tires measure 235/50ZR18 on 8-inch rims, not particularly wide for 320 horsepower. That helps the ride but not the braking distance. We gave the brakes a good panic stop and, as with all Cadillacs, the ABS worked especially well. Recently we tested a V12 Mercedes SL600 roadster ($125,950), and the XLR's anti-lock brakes seem smoother.

The faster the car went the better the speed-sensitive rack-and-pinion power steering felt. The high-speed chassis balance was impressively neutral. The StabiliTrak electronic stability control made corrections to regain traction, but wasn't as intrusive as the Mercedes SL600 and SL500.