It's the twisting, mechanical power all around us -- especially cars. Wheels go round, crankshafts go round, we all get around, thanks to the force applied to a lever, multiplied by the distance to the lever's fulcrum: T= r x F.

Allow me to simplify that equation. Torque to cars is like tannins to wine. You can mention either in casual conversations to impress people without actually knowing what you're talking about.

Auto insiders love torque, and they may be on to something this time.

Torque is one of the reasons so many car people like diesel engines.

While U.S. consumers -- err, I mean politicians -- clamor for "clean automotive" technologies, turning up their noses at vehicles sipping fuel from the same fountains as semi trucks and tractors, we car folks see diesels as a way to have your fun and pretend to be green, too.

Yes, diesels can be clean, meeting even California's draconian emission directives, and also be fun.

They also get significantly better mileage than their gas-only counterparts and often match hybrids without the high-tech surcharge. There's no battery pack in a Jetta TDI, but it can still outperform the majority of hybrids on the road today.

Now there's the 2009 BMW 335d, the single most-fun diesel car available in the U.S.: Instant power, razor-sharp driving characteristics, luxurious interior and a diesel engine that should make every car lover's heart thump with a tick, tick, tick. (It's the injectors making that sound.)

While the popular 335i uses a direct injection, twin-turbocharged, six-cylinder engine to produce an impressive 300 horsepower and 300 pound-feet of torque, the 335d uses a direct-injection, twin-turbocharged diesel engine to create a respectable 265 horsepower and stump-pulling 425 pound-feet of torque.

The engines may sound very similar, but there's a big difference.

The 335d makes enough power to produce tannins in your pants if you're not careful. It's scary driving fun that makes this car such a pleasure. Precise shifts, steering

Of course, torque needs proper mechanics to fully appreciate it. The 3 Series is the perfect place to exhibit.

My six-speed automatic would click through the gears with German precision. It feels like a watchmaker tinkered with the gearbox to make every shift deliberate and exact. You hear the shifts more than you feel them.

The power-assisted steering is nearly as precise. It's firm in your hands but lets you feel the road. The feedback applies back pressure, but it lets you know exactly how well you're carving up a corner. It helps you anticipate the curve so you can blast that delicious torque after the apex.

The car's suspension -- double pivot struts in the front and five-link rear -- keeps it well planted on the road, even through high-speed turns. On the highway, the ride is smooth and quiet, and while there's a sport-tuned feel to the car, it's never obtrusive.

Passengers inside the 335d would never know you're burning blue-collar fuel. And those outside of this sedan are none the wiser, as well. There is that faint tick of the injectors cramming diesel down the cylinders, but it's hardly noticeable.

Plus, there are enough luxury amenities inside to satisfy even the most discerning passengers. BMW carries cache -- people expect quality when they see the distinctive badge. Sense of craftsmanship

My test vehicle, which topped out at $49,000 -- $5,000 over the starting sticker -- provided a leather-lined interior and a sparkling dash with real wood trim that glistened in fresh sunlight from the standard sunroof. I could have been in the Bavarian woods if I hadn't known I was somewhere near Ypsilanti.

It never felt overpriced, though.

The cockpit is compact. The seats hold you firmly in place, and every control is at your fingertips. The red glow from the instruments feels comfortable and reassuring. The gauges are clean and simple.

In the front, there's plenty of room; in the back, not so much. Back there, BMW alleges three adults can fit, and as long as I'm not one of them, I'll take them at their word.

Back row aside, there's a sense of craftsmanship throughout this 3 Series. Even the much-maligned iDrive -- a single knob originally designed to control the world -- has become much less intimidating and easier to use, with the addition of buttons to select some items directly.

The 2009 model year marks a refreshed exterior with a few more curves and hood creases that toughen up the 3 Series. The 335d gets all of those improvements, including new headlamps and tail lights. The additional lines make it a little meaner looking -- and the new diesel engine responds appropriately to the more sinister face. Nothing can be truly mean if it doesn't have the power to back it up. Astonishing performance

Then there are the mileage numbers. Having a car that runs farther is synonymous with better nowadays. The 335d manages 32 miles per gallon on the highway and 22 mpg in the city. Its gas counterpart hits 26 mpg on the highway.

The 32-mpg highway driving might sound OK for many cars, but the performance this car provides makes it downright astonishing.

You buy this car for the experience of sitting in a BMW that can go scary fast and power through turns like it's on rails instead of a road, not for its fuel-saving abilities.

And that's the point car people get when it comes to diesels.

No matter what technology emerges from the efficient energy race, someone is going to figure out how to pump up the power and go faster. I love the prospect of vehicle electrification in the future. Do you know why? Instant torque.

Man only wants to make something good better -- and by better, I mean faster. It's in our genes.

Without torque, our double helix would just be a stepladder of futility. Our twisting and turning DNA is a tribute to torque. The more torque the better.

This BMW lets you improve your mileage, clean up your image and the environment, as well as put a smile on your face every time you start your car.

The way the 2009 BMW 335d meets all 50-state emission requirements is through a urea injection system that cuts NOX emissions -- a common problem with diesels. The urea tank in the car needs to be refilled every 15,000 miles. BMW says this shouldn't be a problem; refilling will be done when oil changes are conducted. Of course, if you choose not to refill the urea, the car will put on a protest of its own. It will refuse to start.

Report Card

Overall : *** 1/2

Exterior: Good: BMW toughened up the face of the 3 Series for this model year and added new headlights and tail lamps.

Interior: Good: Fluid, comfortable dash make this a pleasure for front-seat passengers. Get stuck in the back, and you won't feel as lucky.

Performance: Excellent: The torque is incredible, even at low rpm, making this a racer with extreme capabilities.

Safety: Excellent: A slew of standard safety features including electronic stability control, front- and side-curtain air bags.

Pros : Good mileage, better performance makes this the 3 Series worth driving.

Cons : Not the best choice for someone carrying more than two adults.

Grading Scale

**** Excellent *** Good ** Fair * Poor