It's not too often that we're invited to drive a vehicle that we'll never see on an American road. But that was the case with the just-introduced-in-Europe 2011 Forester 2.0X, which Subaru invited a handful of U.S. journalists to sample in Budapest, Hungary. Why? Well, we can tell you it wasn't for the scenery, as the Hungarian countryside in the middle of January is about as photogenic as dust. No, it was for the 2.0X's all-new engine, which, unlike the Forester we drove, will indeed make its way to America. Codenamed FB20, this 2.0-liter flat-four heads stateside later this year in the 2012 Impreza, of which we got a preview (Impreza Design Concept) at the 2010 Los Angeles auto show.

Subaru aficionados will quickly recognize that the brand's flat-four engine designation has switched from "EJ" to "FB." Some know-it-alls may even notice that the recently launched 2011 North American Forester is already sporting an FB motor. Let's first address the latter. Introduced about a month ago, the U.S.-spec '11 Forester 2.5X highlighted a host of updates -- refreshed front fascia, restyled interior, new wheels, recalibrated suspension -- with the FB25, the U.S. debut of Subaru's third-generation flat-4 "boxer" engine. Displacing 2.5 liters, the FB25, like its 2.0-liter FB20 sibling, represents a clean-sheet design in light of its EJ predecessor. Which brings us to the designation switch. The EJ, which is powering myriad current Subarus including the Outback, was first introduced back in 1989 in the Legacy. In its 20-plus years of existence, the EJ saw 7.6 millions units produced. And before '89, the first-generation boxer, initially available in the 1966 Subaru 1000, was around for 23 years, with 4.1 million examples built. The moral of the story: The FB could easily enjoy a lifespan of around two decades and 8 millions units.

The EJ formula -- 2.0- and 2.5-liter displacements as well as naturally aspirated and turbo variants -- will carry over to the FB. As competent and versatile as the EJ was (and still is), Subaru points out that with stricter fuel-economy and emissions standards on the horizon, the second-gen's aged design meant too many Band-Aids (and costly) fixes to keep it compliant, not to mention competitive; thus, Subaru's impetus for designing the third-gen.