2006 Cadillac XLR-V

Cadillac's ambitions to play on the global luxury stage reach new heights with the XLR-V, on sale now. Consider: a 443-hp supercharged two-seater with retractable hardtop, a showcase for its maker’s technological acumen, priced at a nice round $100,000.

As a flagship sports car for a luxury marque, XLR-V’s closest analog is the Mercedes-Benz SL55 AMG, the performance edition of a classic statement in automotive taste, refinement and engineering. Other competitors include the Jaguar XKR convertible, the Lexus SC 430 and the BMW 6 Series cabrio. Of that crowd, only the Mercedes and Cadillac are true two-seaters.

How does Cadillac fare in this company?

Amazingly well. We drove the XLR-V on a round trip from San Diego inland, over the mountains and through parkland to the desert resort town of Borrego Springs, and it proved far more than competent. It is alternately elegant, smooth and inspiring, delighting its driver in dozens of ways and disappointing in none. Well, unless you really can’t get used to its styling, a brashly American statement that emerges from the intersection of an Eldorado, the F-111 Stealth Nighthawk fighter and Luke Skywalker’s X-wing. Regardless, this is one heck of an automobile, and the most fun we’ve had in a Cadillac.
Last year, although its market segment shrank 17 percent, the XLR gained 7 percent in sales, so its share rose from 12 percent in 2004 to 14 percent in 2005. At the same time it topped the J.D. Power APEAL survey for the segment. Now comes the V version, with a powertrain that takes a back seat to no one.

The XLR shares architecture with the Chevrolet Corvette (GM refers to it as its “performance car platform”). The differentiation between performance variants (Z06 and XLR-V), though, is even more starkly defined than the distinction between base models.

In place of the Vette’s 6.0-liter normally aspirated pushrod V8, the Cadillac mounts the 4.4-liter supercharged dohc Northstar SC, a sophisticated and refined engine it shares with the STS-V. Note the SC displaces 200 cc less than the Northstar VVT on which it is based—the bore is a little smaller to keep the block strong enough for the 12 pounds of supercharger boost while maintaining the quiet character demanded in the luxury segment.

2007 GMC Acadia

Underneath it all lies a chassis built specifically for crossovers, instead of one cobbled together from a minivan. Dubbed “BFI” for “body-frame integral,” the structure offers a low center of gravity, four-wheel independent suspension and rack-and-pinion steering which GM promises will provide a smooth ride with responsive handling. Acadia’s power comes from a 3.6-liter, 267-hp, 247-lb-ft V6 with variable valve timing, linked with a six-speed automatic transmission sending power to the front or all four wheels. That’s enough horsepower to outdo the 2006 MDX and RX 330; however the 2007 RX 350 boosts its own horsepower to 270. 
 

2008 Porsche Cayenne

The base Cayenne’s V6 grows from 3.2 to 3.6 liters, while the V8-powered S and Turbo models now boast 4.8 liters, up from 4.5. Output increases accordingly, though the extra displacement is only partly responsible.

All three engines get gasoline direct injection (Porsche calls it Direct Fuel Injection), a first for the automaker and a harbinger of the powertrain changes we’ll see later this year when the new 911 bows. DFI involves injecting fuel straight into the combustion chamber, where it mixes with air and produces a cooler charge than is possible with more conventional injection into the air intake port. DFI also allows for more efficient combustion and therefore less emissions and better fuel economy.

On top of DFI, the V8 also employs Porsche’s trademark VarioCam Plus system, which adjusts valve timing and lift during high-load situations, and all but the Turbo use intake manifolds with variable-length runners.

Combined, these changes boost the output in the V6 to 290 hp and 283 lb-ft of torque from 247 hp and 229 lb-ft, whereas the Cayenne S now cranks out 385 hp and 369 lb-ft—with more than 90 percent of that available between 2000 and 6000 revs—up from 340 hp and 310 lb-ft. Porsche claims the V6 Cayenne now runs from 0 to 60 mph in 7.5 seconds, while the S will do the same in 6.4.

The twin-turbocharged 4.8-liter V8 found in the Cayenne Turbo now sports a whopping 500 hp and 516 lb-ft, or 50 more horses and 56 more lb-ft of torque than the outgoing model. Porsche says that’s good for a 4.9-second dash to 60 mph and a top speed of 171 mph.

Fuel economy is up, too, with the V6 getting an EPA estimated 19.6 mpg combined; the S gets 16.5 mpg, the Turbo 15.4. Only the V6 comes standard with a six-speed manual transmission, the standard gearbox for the others being the six-speed Tiptronic automatic (optional on the V6).

Cayennes equipped with the air suspension and Porsche Active Suspension Management (PASM) now have the option of getting the new antiroll system, called Porsche Dynamic Chassis Control. At the heart of PDCC are two active antiroll bars, each with a hydraulic swivel motor that twists to counter body motions. Not only does PDCC allow the Cayenne to corner virtually flat, but it also provides an additional measure of damping over uneven surfaces. In off-road situations, with low range engaged, PDCC also will decouple the antiroll bars to allow for maximum wheel travel.