we knew we had a battle on our hands before we even palmed the first key fob. The last time we did a test like this ("Dune Devils," July 2008), the segment consisted of just five vehicles, of which we chose to compare four -- Acura RDX, BMW X3, Land Rover LR2 HSE, and Lincoln MKX. When it came time to select the contenders for this go 'round only two years later, we drew up a list twice as long. So we exorcised the demons from that story -- including the formerly winning RDX -- in deference to the latest in six-cylinder luxury. With the Cadillac SRX not yet available, we chose to cut the decidedly carlike Infiniti EX35, launched last year, in favor of an all-new foursome: Audi Q5, Lexus RX 350, Mercedes-Benz GLK350, and Volvo XC60.

So what gives? Why has this category become one of the most hotly contested segments in the industry? Call it Marketing 101. As boomers tire of truck-based SUVs and the upwardly mobile outgrow sedan life, auto manufacturers are betting on replacements that offer the sporting capability of an SUV in a package not much bigger than a full-size sedan. Hence, this growing small luxury crossover niche.

On paper, these crossovers could be tracings of one another. All seat five and come with six-cylinder engines and all-wheel drive. Niceties including satellite navigation, backup cameras, and poshly trimmed cabins are on offer as well. Of course, there are variations in powertrains and configurations. Volvo's XC60 uses a turbocharged 281-horsepower, 3.0-liter inline-6 while the Audi Q5 employs a normally aspirated, 270-horse, 3.2-liter V-6. Mercedes and Lexus chose larger 3.5-liter V-6s, but the GLK350 mounts its 268-horsepower engine north-south for a RWD-based AWD system, while the 270-horsepower RX 350 sticks with an east-west layout (allows for a lower-priced front-drive model as well as this AWD version). All, except the seven-speed GLK, use six-speed automatic transmissions.