The FB incorporates a 15mm-longer stroke and a 8mm-smaller bore compared to the EJ. The increased stroke, says Subaru, improves fuel efficiency, low- to mid-range torque, and emissions. Thanks to a new valve drive system, not to mention a redesigned cylinder block and cylinder head, the FB maintains the overall size of the EJ, allowing Subaru to drop it in existing products, such as the Forester. (Expect the FB25 to appear in the Outback for the 2012 model year.) The FB also ditches a timing belt in favor of a chain-type cam drive, which delivers a maintenance-free setup and helps keep the width of the engine to a minimum. Other notable improvements include lighter pistons and connecting rods, a higher compression ratio (10.5:1 versus 10.2:1), a cooled exhaust gas recirculation system, and variable valve timing on both intake and exhaust sides.

Rather than boring you with drive impressions of how the never-coming-to-the-U.S. Forester 2.0X handles, steers, brakes, etc. -- trust us, it feels just like the 2.5X Touring we recently tested, just a bit slower -- let's instead focus on the FB20 and how it will impact the 2012 Impreza. First and foremost, the FB comes across as more refined than the EJ, displaying a smoother personality when climbing the rev ladder. It sounds a bit more racy, too, though the boxer flatulence still remains. Given that the Impreza will boast a significant weight advantage over the Forester (probably about 300-400 pounds), it should be good for EPA fuel economy in the 25 city/35 highway neighborhood, and perhaps better - not bad for an all-wheel-drive small car. Zero-to-60 times should fall in the 9.0- to 10.0-second range. To accomplish such fuel miserliness, the '12 Impreza will likely replace its current crop of transmissions - a 5-speed manual and 4-speed automatic - with more modern units, i.e., a 6-speed manual and a "Lineartronic" CVT. A dual-clutch transmission? Never say never, but Subaru is more likely to save a DCT for the next-gen WRX and STI.

With an all-new Elantra, Focus, and Civic out this year, the FB-powered 2012 Impreza is poised to be a legitimate player in the small-car segment. In terms of output and fuel economy, the 148-horsepower and estimated 35-mpg highway FB is a class-competitive engine. And if the chiseled styling of the Impreza Design Concept is any suggestion of the '12's overall competence, then we have a lot more to look forward to than just the engine.

2011 Subaru Forester 2.0X
Base price $19,720 (est)
Vehicle layout Front-engine, AWD, 5-pass, 4-door SUV
Engine 2.0L/148-hp/146-lb-ft DOHC 16-valve flat-4
Transmissions 5-speed manual, 4-speed automatic
Curb weight 3250-3300 lb (mfr)
Wheelbase 103.0 in
Length x width x height 179.5 x 70.1 x 66.9 in
0-60 mph 10.5-12.0 sec (MT est)
EPA city/hwy fuel econ 24/30 mpg (est)
CO2 emissions 0.74 lb/mile (est)
On sale in U.S. N/A