If you've been following the clean-diesel-versus-hybrid "wars" as of late—which is a concept that still strikes me as odd, given that there's plenty of room in the market for both technologies, and both of them are environmentally friendly—the following report isn't going to come as good news. Fueleconomy.gov reports that the EPA numbers are in for the 2009 Jetta TDI clean diesel: 30 mpg city, 41 mpg highway. That's far short of what VW has been trumpeting in recent months, to us and to other publications.

The 30/41 result compares poorly to the Toyota Prius (48/45) and the Civic Hybrid (40/45). It also isn't much better than any number of gasoline-powered cars such as the 5-spd Toyota Corolla (26/35) and the automatic Honda Civic (26/35), especially when you factor in the significantly higher cost of diesel fuel and the (at least) $2,000 premium for the diesel engine itself.

If you scan the forums and post comments around the Internet, you can find numbers to support any argument. There are Prius owners who are claiming they're regularly seeing only 35 mpg, or as much as 55 mpg; some say they drive fast, some say they drive slow, and so on. You'll see the same amount of variance for VW TDI owners, though more of the latter claim to exceed the EPA estimates. That strikes me as odd. Usually, EPA estimates for just about every car on the market are higher than what people see in the real world. That's still true after the 2008 revisions, which had adjusted all the ratings downwards.

At any rate, all of those individual reports are hearsay; they're not scientific tests by any measure. The only real objective results we have is what the EPA gives us. Hopefully we'll get some more controlled data soon—at least from the actual car reviews that appear once the magazines begin testing the new TDI in late June.

Finally, none of this takes away from the fact that the Jetta TDI will likely be a good performer, with sporty handling, a solid European feel, and excellent fuel economy. But 30/41 won't be enough to catapult it into the mainstream sedan market.