Impreza: The un-SUV

Subaru’s vaunted Impreza wagon isn’t an anti-SUV, it’s something even stranger.

All automotive brands have their fanbases and die-hards, but few are as devout as the “Subie” crowd. Born out of the Japanese market invasion of the mid-’90s, where imports wholly overwhelmed domestic American sales, the Subaru faithful are as dedicated as they come. These days, the product lineup is a blend of anything between compact sedans to larger crossovers. But the big deal is the all-wheel-drive and world-class traction management. This makes for a fuel efficient family-mobile that is unfazed by rain, snow, sleet, and hail. These features put it eons ahead of the front-wheel-drive competition. And if you still need to haul the kids but don’t want to give up driving pleasure, the Impreza and WRX blend adult responsibility with childish glee perfectly. Between the traction of AWD, relatively low entry price, seating for five, true manual transmission, and that trademark throaty rumble, the WRX models have an undeniable factor of cool. In the swath of front-wheel-drive econo-boxes that sound like angry weedwhackers, the Impreza is considered a sports car amongst grocery-getters. But while that’s all fine and dandy for the concrete captain, why should an adventurist care about a Subaru? What value off the grid does a low-slung sedan have?

On the surface, not much. The ground clearance is low, the approach and departure angles are minimal, the small engines can’t produce torque low enough to crawl, and the suspension doesn’t have enough travel to keep all four wheels on the ground over rough terrain. Even small gullies will plunge the nose down, sending a rear wheel into the air or high-centering the vehicle. No Impreza can keep up with even the mildest of Wranglers or Tacomas. But that’s the point; the Impreza simply has a different playground.

You’d be surprised how easily the Impreza’s suspension turns bumpy roads into glass. Note: The front wheel is from a Legacy Outback, the rear wheel is a stock Impreza Outback wheel; the used car lot I bought this from ordered the wrong wheel.

The un-SUV

Crossovers and SUVs dominate U.S. market sales, and SUVs and trucks dominate the adventuring world. Usually, sedans and station wagons aren’t even considered by outdoorsy types due to their ground clearance. The Subaru Impreza, and specifically the Impreza wagons, are different.

If you’re not looking to hit a gatekeeper rock crawling trail or clamber deep off of maintained dirt roads, Subies are an ideal vehicle. They blend city livability and fuel economy with muddy-road chops in a seamless way that no other vehicle class can. The station wagons feature as much cargo space as a CUV, but with vastly superior fuel efficiency and driving pleasure. The tight five-speed manuals, controlled suspension, and smooth-revving Boxer engines create thrills that should be reserved for sports coupes. It somehow manages to combine qualities from SUVs, sedans, roadsters, and station wagons in a vehicle that is none of those. It’s not an anti-SUV; it’s something even weirder.

Legendary suspension

While the strength of a conventional 4x4 comes from the axle articulation and large tires to slowly clamber over large obstacles, the 2nd-gen Impreza has a different goal off road: speed. A Subaru might not be able to summit boulders like a Jeep, but that Wrangler is hopelessly outclassed in terms of the smoothness and agility the Impreza has at high speed on dirt, gravel, and rough roads. A combination of suspension geometry, travel, and spring rates allow the Impreza to soak up bumps that would chatter your teeth in other vehicles. It’s not pillow-y and floaty like a Cadillac, either. Subaru didn’t simply lengthen suspension travel and soften the shocks; there’s a control in the damping that’s unmatched in any other vehicle from its generation. Go drive other adventure-mobiles or even sedans from the same era. A TJ Wrangler, Ranger, S10, Tacoma, 4Runner, Cherokee; all of them ride harshly over washboard roads and high-speed trails. Not the little Subie. It’s this special sauce that has allowed Subaru to be a dominant staple in professional rally racing for years. And as always, racing technology eventually trickles down to the consumer market.

Symmetrical AWD

All-wheel-drive is not a revolutionary feature, nor is it unique to Subaru. What sets the Impreza family apart from its rivals is how they tackle the AWD design. Some designs retrofit an existing front-drive or rear-drive system, essentially adding in a full-time transfer case to a 2WD model. Subaru’s AWD system was designed from scratch, allowing them to put much more focus into form fitting the vehicle and the drivetrain together. This allows every vehicle system to work in harmony rather than have the systems fighting each other for traction.

Additionally, Subaru’s AWD is truly full-time. Rather than several modern systems which react to slippage and correct it, Subaru’s system doesn’t wait for the problem to occur; it tries to prevent the problem from happening in the first place. Instead of relying on wheel-speed sensors modulating braking to reduce slippage, Subaru’s center differential manages torque fore-and-aft based on vehicle dynamics. Torque modulation is handled mechanically, not electronically. This means that the drivetrain is able to react as soon as the laws of physics say so, and in many cases, this is able eliminate the hesitation and jerkiness of other AWD systems from the same generation. Modern AWD vehicles are actually front-wheel-drive until slippage occurs, and then the vehicle engages the rear differential to correct it. It’s fascinating how Subaru was able to engineer a mechanical system that still rivals modern electronic systems.

Subaru also mounts their engines longitudinally, meaning the front of the engine is facing the front of the vehicle. This is different than a transverse mounted engine which has the front of the engine facing the side of the vehicle. This means that the transmission is not offset to one side, and the front axle shafts are equal length. Equal length axle shafts will receive, transmit, and react to torque identically. This eliminates “torque steer,” which is the tendency for a FWD vehicle to dart to the right under sudden heavy acceleration since the shorter driveshaft receives torque sooner and at a different rate.

A hotly debated engine

Wander around the online forums and car enthusiast pages long enough and you’ll see the love-hate relationship people have with Subaru’s trademark powerplant. The Boxer engine is a fabulous design in theory. The pistons face outwards horizontally at 180 degrees, rather than inline like a four-cylinder, or in a V-formation like a V6 or V8. This design has three payoffs; vibration reduction, mechanical efficiency, and packaging. Because each combustion event is physically equalized by an identical event on the opposite bank, the shock of each power stroke is minimized. The engine’s rotating assembly sort of becomes its own balancer, and engine vibrations are substantially reduced as a result. This causes more energy from combustion to be transferred into the crankshaft to produce torque, rather than be absorbed by a harmonic balancer, balance shaft, flywheel, or flyweight. In short, more power makes it to the ground per cycle. The third benefit is that this design lays all of the pistons and cylinders flat, making an engine that is incredibly small and vertically short. Because it’s so flat, the engine can be mounted lower in the engine bay, which lowers the center of gravity and improves the handling characteristics of the vehicle. And of course, there’s that trademark “Subie Rumble.” Subaru boxers with performance exhaust systems tend to idle in a deep “wub-wub-wub-wub,” and at full song they let out a throaty roar that’s unlike any other engine family.

The Boxer is not without flaw, however. In large part, this comes from the design of the oiling system and the cooling system. The oil pump is a gear pump, which is a very efficient design for high-rpm engines. The problem is in the oil pan. A pan would like to have baffles in it; little doors and rooms that keep oil contained in an area close to the pump even during extreme angles and high-speed turns. Subaru’s WRX models and a handful of Foresters feature baffled oil pans, but the rest of Subaru’s lineup have to make due without. In a fast corner or an extreme sideways tilt, oil tends to run away from the pump pickup. The pump sucks air instead of oil, and those little pump gears seize immediately. The first cylinder to go is usually #3. I’ve also heard theory that laying the rotating assembly flat causes hydraulic cam followers (lifters) to bleed down more quickly, and resist priming at fire up. This increases the rate of wear because components are grinding metal-on-metal before that crucial film of pressurized oil hits. This is a theory I’ve heard from a long-time master technician and engine builder that I trust, though I’ve never seen this proven with engineering principles.

The cooling system is another issue, and leads to the primary reason people meme on the little flat-4. Subaru’s aluminum is rather soft, and horizontally opposed engine design doesn’t allow for water jackets that are as big compared to other engine designs. This decreases the cooling system’s actual cooling capacity, because it uses up its potential more quickly. Big radiators and good electric fans help take care of this, as does improved airflow efficiency from big grilles and air passages which direct wind into the engine bay while the vehicle is in motion. If the engine does get too hot, however, or the coolant level runs a touch too low, the heat causes warpage on the block’s deck surface or on the cylinder head’s surface itself. Combustion pressure does the rest of the work as a flame front blasts through the weakened seal and roasts that poor head gasket. This might be an uncommon failure, but it’s failure inherent to the Boxer’s design. The general consensus is that any Subaru over 100,000 miles must have its head gaskets replaced, the block redecked, the heads machined, and the head bolts replaced.

The verdict

Subaru wagons don’t do any one thing spectacularly. You don’t buy a one expecting the spaciousness of a Suburban, the capability of a Wrangler, the handling of a Miata, or the economy of a Corolla. If you were to distill the best qualities of an adventuremobile into one vehicle it would not be an Impreza wagon. But the weird little Subie is just competent enough at a variety of things to be a viable option for us outdoorsy types. 4-door sedans and wagons have no business being this practical off-pavement, but we’re so glad that these weirdos exist.