Continued: Run fast, burn clean, cost plenty

I want you. I need you. But there ain't no way I'm ever gonna love you: The message in that memorable slice of Meat Loaf, rendered with a flourish of the rocker's sweaty kerchief, was that two out of three ain't bad.

Diesel fans may feel the same way about the new, 50-state-legal models that began arriving last fall. BMW's dual entries -- the 335d sedan and the tongue-twisting X5 xDrive 35d sport utility -- struck me as perhaps the most desirable specimens yet.

I want their performance, which stacks up against BMW's enthusiast-endorsed gasoline versions. I need their fuel economy, especially the stellar 37 miles per gallon on the highway that I received in the 335d. But on the rare occasions when I stopped to refuel, my ballad-worthy love for the Bimmers was soured somewhat by the volatile price of diesel. At the pump, these BMWs -- like their counterparts from Audi, Mercedes and Volkswagen -- turn into nutty spouses on a credit-card binge.

Nutty has been the word for diesel prices. When I reviewed the VW Jetta TDI diesel in November, diesel fuel sold for $2.95 a gallon nationwide, compared with $2.05 for regular gasoline. That huge premium wiped out the Jetta diesel's considerable mileage advantage. And since the diesel model costs $700 more than the gasoline version (accounting for its $1,300 alternative fuel tax credit), its money-saving argument seemed less compelling.

But earlier this week, a gallon of regular was averaging about $2.25, according to AAA, while diesel prices had plunged nearly 25 percent to an average of $2.28 a gallon. For BMW, Audi and Mercedes, which call for premium-grade fuel in their gasoline models, the comparison is more favorable: Diesel now is only pennies a gallon from the cost of premium and delivers 20 to 40 percent better mileage.

Only months ago, energy experts were adamant that diesel, largely because of refinery shortages, would remain prohibitively expensive for years. So much for the experts, who have proved again that petro-predictions are as reliable as a 12-month weather forecast. For now, diesels again are poised to save you hundreds of dollars a year in fuel.

Reduced emissions

But diesel isn't strictly a dollars-and-cents affair. The latest generation of engines emits about 20 percent less carbon dioxide than comparable gasoline engines.

Diesel owners have also come to expect great durability, with diesels routinely running for 200,000 miles or more with no costly repairs. The engines conserve liquid like camels in the Sahara: Both the 335d and X5 35d can travel nearly 600 highway miles on a tank.

But perhaps the coolest thing about the new diesels is that they make you feel as if you're getting away with something: They are frugal, yet fun to drive.

BMW, ever mindful of what justifies its lofty prices, has whipped up the most power-hungry, enthusiast-oriented diesel ever sold in America. The 335d engine, the nation's first twin-turbocharged diesel, produces 265 horsepower and 425 pound-feet of torque from a mere 3 liters of engine displacement.

A smoking 5.8-second run to 60 mph puts the diesel a mere half-second behind the gasoline-powered 335i and its ferocious 300-horsepower, twin-turbo 6. In my life, I've never experienced such explosive throttle response from a diesel.

The BMWs aren't pure mileage hounds in the manner of the small VW diesel, which delivered 48 mpg on the highway. The BMW will sneak past its federal estimates of 23 mpg in town and 36 on the highway, but it takes effort. Romping like a schoolboy in the 335d, I still managed 30 mpg on the highway. All told, in city and on highway, in fast times and slow, I managed 30 mpg over a week of driving, an enormous gain over the 21 mpg I got with the gasoline 335i.

BMW said it couldn't build a manual transmission that would be strong enough to handle the diesel's torque and still feel sporty. And as much as I love self-shifting a BMW, it must be said that the diesels are especially compatible with the six-speed automatic transmission. With torque packed into the lower and middle range of the power curve, you can leave the car in "drive'' and enjoy ridiculous passing power in any situation.

Like other modern diesels, the BMWs are California-clean and do away entirely with black, stinky exhaust. The 335d's downer is a $44,725 starting price -- $2,475 above the formidable 335i with an automatic. A $900 federal alternative fuel tax credit barely softens the blow. The X5 makes a stronger economic case, at least if you are determined to buy a luxury SUV. Starting at $52,025, the diesel model costs $4,600 less than the X5 with a 4.8-liter V-8. Figure in a $1,800 federal tax credit and the buyer is $6,400 ahead before the first fill-up. All told, the 335d can save time. But it's the X5 xDrive 35d that saves more money.