You're sitting a stoplight in your new 263-horse Mazdaspeed3. The street ahead is clear. When the light flashes green, you're going to excuse yourself from the rest of the herd rather rapidly -- including that brand-new 2011 BMW X3 xDrive35i right next to you. Dispatching it shouldn't be a problem, right?

Well, you had better hope whoever is behind the wheel of that crossover doesn't have similar aspirations. Because while you artfully Fred Astaire the Mazda's pedals, balancing wheelspin and boost to maximize acceleration, they'll merely slide the transmission into sport mode and step on the gas. Then the X3 will reach 60 mph in 5.6 seconds, matching your Speed3.

Let's say this impromptu (and totally hypothetical) drag race goes a quarter mile. It'll take the X3 all of 14.2 seconds and 96.7 mph to get there, which -- wouldn't you know it? -- is 0.1 second and 3.2 mph behind the Mazda, assuming you're driving it very well.

How does a roughly 4200-pound crossover like the X3 do that? You can thank BMW's stalwart N55 straight-six, the eight-speed automatic it's attached to, and the turbocharger hanging off the side. The spread of those eight gears (sixth is one-to-one, seventh and eight are overdrive) makes brilliant use of the 300 horsepower and pound-feet of torque during not wholly improbable stoplight drag races, giving the engine five closely spread ratios to flex its powerband.

When you relax your right foot, the transmission quickly reaches for the overdrive gears, aiming for the 19 city and 26 freeway mpg the X3 is rated at, which -- wouldn't you know it (part two)? -- happens to be 1 mpg better than the Mazdaspeed3 on both ends. But let's stop picking on the Mazda, because the X3 has flaws of its own. Under normal driving, its transmission can feel clunky while leaving from a stop, especially when shifting into and out of second gear.