The blogosphere will a hundred times echo today’s announcement that Mercedes-Benz will offer hybrid versions of its C-, E- and S-class vehicles in the United States and Europe in about three years. Automotive News quoted Herbert Kohler, head of Daimler’s E-Drive and Future Mobility unit, who said, “We have a leading position in the premium segment concerning alternative propulsion systems, and we will defend it.”

A Daimler source said the C- and E-class full hybrids will be launched in Europe before 2013 and an S-class plug-in hybrid will be launched in 2014—followed by releases in the U.S. about six months later.

Do these announcements of an imminent bright future for Mercedes hybrids sound familiar? That’s because Daimler comments about future hybrids date back at least seven years. In Feb. 2004, Automotive News reported that Daimler will produce hybrids “in the coming years.” At the time, Daimler CEO Deiter Zetsche sounded skeptical. “Although hybrids have been a roaring PR success, the jury is still out if they can be a practical, long-term business-case driven success,” Zetsche said.

Three years later, in Sept. 2007, Zetsche appeared more resolute (or you could save defensive). “We are no longer developing any cars without a hybrid option,” in an interview with Der Spiegel magazine. Following a year of roller-coaster gas prices and intensified environmental legislation, Automotive News reported in Jan. 2009 that Zetsche said Mercedes would “launch at least one new hybrid vehicle a year.”

How many future Mercedes vehicles will carry its hybrid badge?

In Aug. 2009, the company’s first hybrid, the Mercedes S400 mild hybrid, reported its first month of sales: 22 units. The $91,000 sedan has a combined city-highway mileage rating of 23 mpg. By October, Zetsche promised a hybrid version of each of Mercedes’s high-volume cars and a plug-in hybrid in 2012.

By the end of the year, the company had introduced its M-Class SUV hybrid. The Mercedes ML450 is only available for lease—either 36 or 60 months at $659 or $549 per month, respectively. Mercedes cited “limited supply of batteries” as the reason. Mercedes, just getting into the market, managed combined sales/leases of 601 units for the two vehicles for 2009.

Did the company pick up the pace in 2010, as it moved toward becoming a competitive hybrid brand? Not quite. With a few years of production and sales under its belt in 2010, Mercedes put fewer than 2,000 hybrids on U.S. roads— 955 of the S400 mild hybrid sedan and 766 of the ML450 hybrid SUV. Meanwhile, Toyota in 2010 sold more than 15,000 units of the Lexus RX 450h luxury hybrid SUV, and more than 10,000 units of the HS 250h hybrid sedan.

Therefore, when Daimler’s Kohler now talks about a leading position with alternative propulsion in premium, he must be referring to diesel. The company has four so-called “clean diesel” vehicles offered in the United States, and sold 7,558 of them in 2010. (To its credit, Mercedes is planning to shift high volume sales to the new 2012 Mercedes C250—its gas-powered four-cylinder model with direct injection and turbocharging—delivering combined mileage of 24 mpg.)

So, should we be encouraged by today’s announcement that Mercedes will have new hybrids, and that a plug-in hybrid is on the way? Sure. Every new consumer option for a vehicle with a more efficient hybrid drivetrain is a good thing. But until Daimler delivers these vehicles with even better improvements in fuel efficiency, at a competitive price, and in higher volumes, it looks like CEO Deiter Zetsche and his company are still in 2004 mode—seeing hybrids as a PR effort and not a long-term solid proposition.