The recipe for Subaru’s compact Impreza is getting a rewrite for 2012.

Previously, it was like a bag of trail mix that skimped on the M&Ms. The Impreza was a hearty, go-anywhere offering that was long on nutrition but short on a key ingredient to sweeten the concoction and broaden its appeal.

That ingredient was fuel economy, and for 2012, Subaru added it by the handful. The company now brags that this new model, available as a sedan and a hatchback, is the most fuel-efficient all-wheel-drive vehicle in the U.S.

Throw in a touch of new styling and the acclaimed Subaru constitution of an ice-fishing nudist, and the 2012 model is impressive indeed.

This Impreza starts at $18,245, and versions with the most fuel-efficient transmission are now rated at 27 miles per gallon in the city and 36 mpg on the highway. That’s an impressive jump when you consider the previous version got 27 mpg on the highway.

To make these gains, something had to give. No automaker can pull a 33 percent jump in fuel efficiency out of the ether. In the 2012 Impreza, it’s done with a smaller engine and a more efficient transmission.

Power now comes from an all-new 2.0-liter, four-cylinder boxer engine (so named because the pistons move toward one another simultaneously, like a pair of boxers touching gloves before they fight). The engine produces 148 horsepower and 145 pound-feet of torque. That’s a drop of 22 horsepower and 25 pound-feet of torque from the previous Impreza’s 2.5-liter engine.

In this age of 500-horsepower family station wagons, it’s rare for an automaker to cut output so precipitously from one model year to the next. Yet dropping the Impreza’s horsepower down to 148 brings it squarely in the range of other compact cars such as the Honda Civic, Hyundai Elantra and Chevy Cruze.

Those cars all get better mileage than this Impreza, but they’re also all front-wheel-drive and don’t carry the weight and mechanical penalties that all-wheel-drive typically puts on efficiency. This Impreza now makes a strong argument for Snowbelters looking to avoid compromise; in 330 miles of driving, I averaged 26.5 mpg.

Around town, the Impreza’s new engine is nice and torquey, so drivers never feel like they’ve made a great sacrifice in power. The lesser power figure is a little more noticeable on the highway, but it is all you’ll need for a car this size.

The car is nicely balanced and handles well, aided no doubt by all four wheels providing grip. Subaru added a new electric power steering system for greater efficiency. That it provides commendable road feel is noteworthy only because so many other electric systems don’t. Also helping handling and efficiency is a curb weight that is almost 100 pounds lighter than the previous Impreza.

My only complaint about this Subaru on the road was the amount of engine noise. Get the Impreza anywhere above 3,000 rpm, and the entire cabin is dominated by a strained groan that has you reaching for the volume knob or asking your fellow passengers to speak up.

This aural encroachment can be partially blamed on the continuously variable transmission that came on the loaded $25,645 Sport Limited hatchback I tested. As you probably know, CVTs don’t shift from one gear to another, but instead infinitely adjust the car’s gear ratios. This maximizes efficiency but also tends to keep the engine operating at a higher rpm than it would with an automatic transmission.

This Impreza’s CVT also dials up the sport quotient a bit with steering wheel-mounted paddle shifters that enable drivers to manually select six preset gear ratios for more control when needed.

If you prefer a true manual or want to save some money to keep things quieter, lesser Imprezas come standard with a five-speed manual transmission and offer the CVT as a $1,000 option. But be warned that fuel economy takes a small hit with the manual.

Aside from the loud engine and some errant wind noise that leaks into the cabin, the Impreza shuttles its passengers in comfort.

The cabin’s layout is clean, simple and made from high-grade materials that competitors should take note of. The seats are supportive, visibility is excellent (on the hatchback at least) and there’s plenty of room in every seat for the tall among us.

My loaded tester came with leather seats that were heated in the front, a touch-screen navigation system with XM satellite radio and traffic, a moon roof, trip computer, fog lights, Bluetooth and heated mirrors. Everything worked well save for the navigation system, which was a slow loris of a unit and had repeated trouble figuring out where it was.

All Imprezas have as standard safety equipment stability and traction control, four-wheel disc ABS and seven air bags (including a driver’s knee air bag). The 2012 Impreza is also a top safety pick by the Insurance Institute for Highway Safety.

Wrapping around all this content is a redesigned exterior that brings the Impreza more in line aesthetically with the rest of Subaru’s lineup. This company’s products have never been known for their styling, and this Impreza makes no effort to change that.

That’s not to say the Impreza sedan and hatchback are bad-looking vehicles; they’re not. The look is funky enough to please the brand’s faithful, yet mainstream enough to appeal to a variety of buyers. My Limited Sport hatchback tester nicely balanced a sporty and rugged demeanor with standard 17-inch rims finished in a dark gray and roof rails.

For denizens of ski slopes or voyagers on mountain-biking trails, groups traditionally pro-Subaru in their buying habits, this Impreza hits all the marks. Although it’s a little noisy at times, the car is as functional, well-built and economical as it’s ever been.

Meanwhile, for a more mainstream audience that may have been turned away by the Impreza’s once-eager drinking habits at the pump, this Subaru adds a sweet bonus to an already healthful snack.

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2012 SUBARU IMPREZA 2.0I:

—Base price: $18,245 (including destination charge)

—Price, model tested: $25,345, Sport Limited five-door

—Powertrain: 2.0-liter, DOHC, four-cylinder boxer engine; continuously variable transmission with paddle shifters

—Horsepower: 148 at 6,200 rpm

—Torque: 145 pound-feet at 4,200 rpm

—0-60: 9.8 seconds

—Curb weight: 3,086 pounds

—Wheelbase: 104.1 inches

—Overall length: 173.8 inches

—EPA fuel economy: 27 mpg city/36 mpg highway

—Final thoughts: Subaru gets sweet on its already nutritious snack.