No one knows why. Einstein spent years attempting to derive a Grand Unified Theory of Racing Stripes.

Consider TV detectives' Starsky and Hutch's 1975 Gran Torino, a mentally defective farm animal of a car weighing 4,400 pounds and powered by a starved-for-air 250-horsepower Cleveland V-8. This engine did for muscle cars what pink feather boas do for Marine dress uniforms.

And yet, with those big white hockey stick racing stripes on the sides, the Gran Torino was indisputably quicker. Somehow time contracted.

Now consider our test car, a 2010 Suzuki SX4 SportBack. Ordinarily, you'd assume such a car — a tiny five-seat troll, with a rear hatch that looks like a ripe diaper — would just be nailed to the asphalt. But add some rally stripes on the hood, more along the aero side skirts, and top it off with a silvery meatball on the hood and voila, you've got a racy, capering little hot hatch that's actually respectably quick. Figure zero to 60 in 8ish seconds.

In addition to the paint job, the SX4 SportBack gets sassy little roof and chin spoilers and some other distinctive body bits.

Feverish, strung tight, with an exhaust note that sounds like Santa's elves caught in a wood chipper, the SX4 SportBack is the perfect car for those who think perfection is overrated.

The donor car for the SportBack is Suzuki's SX4 Crossover, which I've been touting since first driving it two years ago as one of the auto market's most under-appreciated values. With all-wheel-drive, standard navigation system and loads of power accessories and convenience features, for around $18,000, the SX4 Crossover stands just about alone in the desirable econobox all-wheel-drive segment.

The SportBack is the same car, only set to Kill. Gone is the prop shaft driving the rear wheels, eliminating the weight and driveline losses of an AWD system. The 2.0-liter four cylinder gets a slight bump in horsepower (5 percent) to 150 horsepower and similar uptick in torque (to 140 pound-feet).

Transmission choices are either a six-speed manual or a paddle-shifted continuously variable transmission. Our test car was kitted with the six-speed manual, and one of the perverse pleasures of this car is downshifting cruelly and revving the engine against the rev limiter like a maniac.

The sound? The sound. ... Let me see. Imagine Lucy Ricardo stomping grapes in the vineyard, only the barrel is full of cats.

The Suzuki makes a virtue of a functional liability, and that is its total vacuum of low-end torque. At any point under 4,000 rpm this engine is bereft of twist. If you attempt to take off from a stop in second gear, the car has the acceleration of a Russian novel. But above 4,000 rpm the torques come on hard and fierce, and if you cane it, it actually seems to like it.

As you've heard me say before, it's more fun to go fast in a slow car than slow in a fast car.

It's also a lot more economical: This Suzie gets 30 mpg on the highway.

The underpinnings of the SX4 SportBack are suitably reinforced: Lower ride height, stiffer springs and shocks, 17-inch wheels and racy Dunlop tires. That's the car you get when you drive off the Suzuki lot.

However, our test car had been further breathed upon by Suzuki's favorite tuner shop, Road Race Motorsports in Sante Fe Springs.It added a less-restrictive exhaust system, a cold-air intake. All that's good for maybe 10 extra horsepower. RRM kicked in beefier springs, a stouter anti-roll bar and racetrack-ready Dunlop Direzza Sport Z1 Star Specs (215/45-17's).

Here, at last, we come to wellspring of all the fun I had. Tires are the most important part of any car's ride-and-handling package, and these tires are just about the meanest, stickiest gum balls on the market. The fact is you could mount these tires on Sealy Posturepedic and it'd handle well. The SportBack bit nicely on turn in. The steering was alert and lively in my hands. And the extra grip put more iron into the brakes. Excellent.

And so a reasonably flat-cornering, grippy and predictable little hatch is transformed into an ornery little vampire with the simple application of rubber.

And stripes. Don't forget the stripes.

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SUZUKI SX4 SPORTBACK

Base price: $17,949

Price, as tested: $20,000 (est.)

Powertrain: 2.0-liter DOHC 16-valve with variable valve timing; six-speed manual transmission; front-wheel drive

Horsepower: 150 at 6,200 rpm

Torque: 140 pound-feet at 3,500 rpm

Curb weight: 2,732 pounds

0-60 mph: 8.0 seconds (est)

Wheelbase: 98.4 inches

Overall length: 162.8 inches

EPA fuel economy: 22/30 mpg, city/highway

Final thoughts: Good, clean noisy fun