With hot versions like WRX and STi, I bet few of you are actually interested in reading this article. Anyway, it’s my policy to describe every car no matter interesting or boring. So let us have a brief view into the regular Impreza first. 

Subaru Impreza does not intend to compete directly with mainstream family cars like Toyota Corolla and Honda Civic, primarily because its scale of investment cannot match with those giant car makers. Instead, Impreza’s strongest selling point is the adoption of permanent 4-wheel drive, and the image benefited from the rally car. You can argue whether a family car with 100 horsepower or so really need 4WD, which makes the Impreza 100 kg heavier than its mainstream competitors. However, as target sales number is relatively small, Subaru won’t find it difficult to attract sufficient customers who think the extra security on snow or wet justify the added weight and cost. 

Sedan or Wagon, the bread-and-butter 1.5-litre Impreza weighs 1240 kg, which proves to be too much burden for the 100 horsepower output from the little sohc 16-valve horizontally-opposed 4-cylinder engine. (European gets a 1.6-litre version with only 90 hp) Beautiful sound aside, there is no much to praise. 0-60 mph takes 12 painful seconds, making you wondering why not buy a Ford Focus 1.8 instead. 

With only 100hp, any discussion of the advantage of 4WD is nonsense - at least on dry. There is simply not enough power to exploit the potential of the rigid chassis which is 148% stiffer than the first generation. Safety, however, was the primary objective of the chassis upgrade. The suspension set up is too soft, not just compare with WRX but also by class standard. The car floats on bumpy surfaces, without the planted feeling of European hatchbacks. Cornering limit is low because of using narrow tyres. The steering is very light and unlike WRX, provides little feel from the road. On the positive side, it steer quite neutral and rolls little in corner. That’s all.  

The 2.0-litre engine might be better, though I have no idea how it actually behave. This is the normally aspirated version of the EJ20 that powers the WRX. In Japan, it is equipped with AVCS variable valve timing to enable a peak power of 155 hp and a broader torque delivery. Nevertheless, weighing 1320 kg, it is still not a fireball that the price tag suggest, or in other words, too expensive for such a small family car. 

Small ? yes, although the second generation Impreza has already been stretched by 55 mm in length and 30mm in height, the wheelbase gains just 5 mm to 2525 mm, compare with class average of nearly 2600 mm. Although journalists said there are more room for rear passengers, it’s still short of leg room compare with nearly all C-segment rivals, especially Civic, Corolla and Focus. Up front, however, is as spacious as anyone else. Like the WRX, both driving position and visibility are excellent. The much improved dashboard now looks with a little bit style and quality, if not time-resistant. 

In contrast, what you might resist in the first sight is the new face dominated by odd-looking circular headlamps. In fact, not just the front, but the whole car looks odd no matter from where you view. Still want permanent 4-wheel drive? look and think twice ! 
 

Impreza WRX

Strangely, the first generation WRX was not a brilliant design in first sight, but the more you looked the more beautiful it grew on you. So after 8 years of falling in love with it, it’s hard to accept a successor so ugly. Ugly ! pardon me, I rarely use such a subjective description but I can’t help feeling sad about its styling. No matter how many times I saw it, its strangely undynamical rectangular shape, odd big circular headlights and complicated face still conflicts with our inherent sense of beauty.  

OK, we don’t judge cars purely on styling, especially for this kind of A-to-B driver’s cars. Let’s see the chassis - 2.5 times as rigid in torsion as the outgoing car guarantees superior handling, ride and of course, should pass the strictest safety regulations. This is what the project manager most proud of. The next thing is improved interior space while preserving a short wheelbase, which grew just 5mm, thus guarantees nimble handling. I’m not too convinced about this one, considering the new WRX has got much longer front and rear overhangs, hence an extra 55 mm of overall length. Worse of all, the bigger and stronger chassis accompany with all other enhancement adds 100 kg to the car, despite of aluminium bonnet. (note: various figures were quoted by different sources because they compare the new WRX with different "old car", say, American sources compared with 2.5RS, UK sources compared with Impreza Turbo. However, according to Japanese official figures the new WRX weighs 1340 kg, versus the 1240 kg of the previous non-STi WRX Version VI) 

The suspension is still all struts set up, which has been proved successful by various WRC teams. Yes, in the world of rallying MacPherson strut is more favourable than the mighty double wishbones because it provides better camber control for long-travel suspensions. In the new WRX, the struts are attached to the strengthened body with new front sub-frame and revised geometry. Front suspension lateral links are made of aluminium (excluding US version). The roll center has been raised by 33mm though I have no idea what this suggest. (we do not say roll center the higher the better or the lower the better)  

Tracks have been widened as the body is 30mm wider, this should help cornering stability. Wheels are still 16-inch wearing 205 width tyres but there is optional 215/45ZR17 which is also standard in UK’s version. Brakes are no pizza size, with diameter just 294mm front and 266mm rear, thus it’s still a relatively weak link of WRX. It seems that Subaru has reserved the best brakes for STi version. 

What matter most to WRX enthusiasts, however, is the fire-breathing power plant, which gains least improvement or perhaps even a bit deterioration due to stricter emission laws. The basic engine is still that 1994 c.c. boxer 4-cylinder, code name EJ20, still all-alloy design, still having 4 camshafts, 16 valves and a single IHI turbocharger mating air-to-air intercooler. What’s new? Subaru will tell you it’s 80% new, but more specific wise there are only AVCS variable valve timing at the intake side and a 11% larger intercooler. Thanks to the variable valve timing, Subaru claims the torque curve is much more flatter, with 80% of torque available from 2200rpm. Remarkable? I don’t think so. There are some European turbo engines can deliver 90% torque at 2000 rpm. Even the high-boost Audi RS4 can reach peak torque at just 2500 rpm ! 

Peak power and torque are 250 hp and 246 lbft (both JIS), compare with the last 280 hp Japanese WRX Version VI (still non-STi, remember), there is a deficit of 30 horsepower and a weight penalty of 100 kg ! Blame to the new emission regulations which requires 3 catalytic converters including a close-coupled cat near the exhaust collector (to deal with cold start emission, see Technical School). No matter how flatter the torque curve is, undoubtedly the new WRX will be much slower than its predecessor in acceleration. 

The above applies to Japanese version only. For the first time, UK and US are offered with WRX officially and their output are even lower. UK’s car (which is identical to Australia’s) has 218 hp / 215 lbft while US version has 227 hp / 217 lbft. Most journalists, such as Car And Driver and Autocar, blamed that to stricter emission requirement but few of them noticed the export engines do not have AVCS while the turbine is also smaller in diameter. The latter means the Japanese pumps out a maximum boost of 17psi instead of the export versions' 14.2psi. When deciding to drop these good things, cost may be the biggest concern. But someone also believe the Japanese prefer to keep the best thing exclusively for themselves ! Lastly, the UK and US versions also differ from the Japanese car by a 8.0:1 compression ratio versus 9.0:1, which is probably because of emission reasons. 

The engine still drives through a 5-speed manual to all 4 wheels via 3 differentials, among which the center differential is viscous-coupling LSD while the rear is Suretrac (torque biasing) mechanical LSD by AP. Center LSD normally distribute 50/50 torque to front and rear. In case of wheelspin, it will send more torque automatically (rather brainlessly as well) to the opposite axle which has more grip. Need front LSD ? go for the STi version later. In short, the transmission system remains nearly unaltered from the old WRX. 

On the Road 

Now let’s see how well our technical analysis match the real world experience.  

Start the engine, you’ll hear the typical boxer noise. Turbine smooth, rev-happy and red-lined at 7,000 rpm seems everything a world-class engine possess, but it lacks one important thing - real power. No matter how it rev and scream, the car does not accelerate like a fireball - a term that used to describe the old WRX. Even compare with the UK-only old Impreza Turbo (215hp), the new UK version WRX (218hp) takes 0.4 more seconds to finish 0-60mph. That’s 5.7 seconds (250 hp version claimed as 5.3 sec), not bad, but deterioration is hardly acceptable. 

Subjectively, it feels even slower. On the one hand, the so-called improved torque curve can be hardly detectable. On the contrary, the extra 100kg burden even made it worse. Off-boast, throttle response is disappointingly sluggish. Below 3,000 rpm, power delivery is weak and turbo lag is noticeable. However, it revs into live since 3200 rpm where full boast is obtained, then the torque increase linearly and eagerly towards the 7,000 rpm red-line. No matter low or mid-range, however, Audi S3 feels decisively more powerful, flexible and responsive. In reality, S3 also produces stronger mid-range acceleration, in-gear acceleration as well as 0-100 mph. Both cars have more or less the same power rating and kerb weight, so the differences lies on the way they deliver their power. 

On the other hand, the improved sound-deadening and vibration-free chassis makes the car feel even slower subjectively.  

In contrast, handling is benefited by the rigid chassis. The whole structure feels stiffer and more secure. It does not twist or bend like the old car on poor surfaces. As a result, the suspension has been set up to provide compliant ride million miles ahead of the old car which was never praised of ride comfort. This is a road-going rally car you will love to go shopping with.  

Is there any improvement in body control or grip? hard to tell, but it is sure that now the car steers more neutrally and display safe understeer much later. There’s almost no understeer unless reaching its limit. Throttle steer? no problem. The steering feels a bit too light and not sharp enough in initial feel, but drive it longer and you’ll discover it actually provides good communication and accuracy. And there is no kick-back or vibration from steering column which characterised both the old WRX or Lancer Evo.  

Gearshift now has less resistance and still a short and snappy throw. Brakes are effective but pedal feel is too light to inspire confidence.  

Compare with Audi S3 again, the WRX wins decisively in handling. It has better controlled ride over poor surfaces, better high speed body control, more steering feedback and more fluent control overall. 

In the end, the WRX is still the ultimate driver’s car in its class. There’s nothing can compare with it once in a twisty road. Performance is its biggest weakness, so is look and packaging. In my opinion, STi or Evo 7 are much better bet and worth the extra money. 
 

Impreza WRX STi

As before, the hottest WRX is the STi version. If you have never heard the name, let me explain again: STi standards for Subaru Technica International. Many people say it is equivalent to BMW’s M-division but I think it is better to be compared to AMG or HSV. In many ways it operates like an in-house tuner, concentrating in modifying cars in a human-intensive technique and supplying racing parts to tuning market. About one-forth of all WRX produced will be the STi version. 

The biggest improvement from standard WRX is undoubtedly more power, which is much welcomed because the new WRX is too heavy. Base on the same variable-valve-timing boxer engine of the Japanese version, STi installed some racing components - lightweight forged pistons and connecting rods, lightweight hollow valves (sodium-filled for better cooling) - to raise rev limit to 8,100 rpm. Then increase boost efficiency by employing a 50% larger (compare with old STi) intercooler and reposition it to take advantage of air flow. This should lower intake air temperature thus improve volumetric efficiency. As before, the STi intercooler incorporates water spray facility to enable flat-out use for long time. 

The turbocharger is also upgraded. By attaching a resin ring to the inner surface of turbine housing, the gap between turbine and its housing becomes negligible - therefore it is called "zero-slack turbo". This reduce leakage thus raise boost pressure. At the exhaust side, a 100 mm diameter exhaust pipe is used to reduce back pressure. Lastly, to withstand the increase power, the engine block is stiffened.  

Without surprise, the new STi equals its predecessor in peak power - both reaches the domestic voluntary limit of 280 hp. Insiders said the actual figure is around 310 hp, which might not beat the old one by much but in terms of torque it is undoubtedly superior - 275 lbft versus 260 lbft. Torque delivery is particularly stronger at mid range, from 3,000 rpm to 5,500 rpm. (Due to tougher emission standard, European version of STi is less powerful - 265hp and 253 lbft. It is also 40kg heavier, thus performance is less impressive.) 

Unlike the standard WRX, you’ll feel the STi has real power. Turbo lag is lighter (but still too much compare with Audi or Porsche), throttle response is sharper, more punch is available all the time. But compare with the standard car means nothing. Take an old STi Version IV, V or VI, you’ll feel the extra punch fails to deliver the same kind of performance in straight line because it carries an extra 155 kg. Subaru knows that, so it gave STi the company’s first 6-speed manual to quicken acceleration. It’s a good transmission, with metallic feel and ideally-spaced ratios, but I doubt if it can do 0-60 in 4.6 seconds like its predecessor. 

What it lost in straight line is gained back in corners. The new WRX chassis is already very strong and has wider tracks, the STi further improve it with titanium strut tower bar and inverted dampers. The suspensions employ forged aluminium lower arms and is set 30% stiffer than the standard car. For the 4-wheel-drive system, viscous-coupling center LSD and rear Suretrac torque-biasing LSD remains unchanged, but the front axle also got a Suretrac. Stripped-out version Type RA still employs a variable split ratio center differential instead of viscous-coupler. It allows the driver to choose from the 6 fixed front-to-rear torque split ratios, sounds interesting but no way as clever as Mitsubishi’s active differential. 

The STi feels home on windy B-roads and wet surfaces. It rides firm but soak up bumps far better than Lancer Evo VII. While it might not corner as agile as its arch-rival, it handles better than the standard WRX in all aspects. The steering feel is slightly heavier and quicker, turn-in is sharper, brake pedal feels meatier, Brembo brakes are powerful and fadeless, gearchange is superior, wider tyres generate superior grip, higher cornering limit accompany with less understeer, body roll is minimized .... Subaru claims it can lap Nurburgring 4 seconds quicker than the old car despite of slower straight line acceleration. This prove how much better the new car corners.  

This must be the world’s second-best cross-country driver’s car - just behind the new Lancer Evo VII. For those cannot put up with the Evo’s harsh ride, WRX STi is definitely the only choice. 
 

STi versus Lancer Evo VII

STi and Evo has been arch-rival since 1994. The complete renewal of both cars brings the competition to hottest level. Generally speaking, people agree that the new Evo is quicker but the Impreza is easier to live with.  

The Evo’s engine is more responsive to throttle and has less turbo lag. It needs a few hundred rpm less to get into power band and at the peak delivers 7 lbft more torque than the STi. Carrying 30 kg less, the Evo feels obviously quicker all the time. The STi strikes back with the new 6-speed gearbox, not only having one more ratio but also shifts slicker. 

ACD and AYC gives the Evo incomparable cornering ability. It laps Japan’s Tsukuba race track in 1 min 4.5 sec or 1 sec quicker than its rival. Steering is more responsive while it can enter corner at higher speed and power out earlier. STi understeer quite a lot. 

However, the Subaru rides more compliant. To many people, Evo rides too harsh thus is not an ideal machine for distant travel. 
 

Impreza facelift

Poor sales proves that people hated the design of the bug-eye second-generation Impreza. Therefore after just less than 2 years, Subaru made an early facelift to the Impreza. The restyle was penned by Prodrive design chief Peter Steven. It has a much revised front end, from a pair of smaller headlights to reshaped bonnet and bumpers. It certainly improves visual appeal. 

The look of STi has even more changes - the intercooler intake duct on bonnet becomes more pronounced to improve cooling. Intercooler and water spray were also improved slightly. As a result, the engine feels a little more punchy and a little quicker in acceleration. Another important change is the use of a big rear wing to improve high speed stability.  

In comparison, chassis changed little. Basically the modifications involve just minor tweaks to suspension bushings. The European version WRX gets 7 more horsepower. 
 

Prodrive STi

In Europe, tougher emission regulations led to a considerable reduction of power and torque to the STi. To restore the lost ground, Subaru chose a tricky but now increasingly common way to by-pass the EU type approval: it offers a performance upgrade kit via its subsidiary Prodrive. Seen as an aftermarket kit, it doesn’t need to get type approval. The kit costs £2000 including installation, thus the whole car still costs less than Evo VII. 

The kit is actually just a re-mapped ECU chip. It releases the full potential of the previously self-limited turbocharged engine. Peak power and torque jump to 300 horsepower and 299 pound-foot respectively, that’s even more than the Japanese version STi (although its 280hp is also self-restrained). The torque now spreads over a wider band, comes earlier at the rev and last later. In particular, from low to mid rev range the stronger torque delivery makes a big difference to acceleration and overtaking. Now performance is on a par with Evo. The 1470kg Prodrive STi is claimed to be capable of topping 155mph and finishing 0-60mph in 4.7 sec. 

Other changes are just limited to cosmetic (bumpers etc.) and a big rear spoiler which has already been applied to standard STi since the facelift. 
 

American STi 2.5

American car lovers used to be treated as "second-class citizens" by Japanese car makers. They are usually offered with less powerful cars compare with Japanese or European markets. Now Subaru is going to change this by introducing a 300-horsepower Impreza WRX STi to the US market. This car has more power than its Japanese and European sisters, which should make the latter jealous.  

While other STI have a 2-litre engine, the American version gets a 2.5-litre version of the boxer four. More capacity allows it to run at lower turbo boost pressure - 14.5 psi instead of the Japanese version's 17.5 psi - yet produces 20 more horsepower (although the Japanese figure is somewhat understated) and 25 more pound-foot of torque. Performance is therefore sparkling - expect it to match the European Prodrive version which also has a 300hp / 300 lbft output. However, unlike the Prodrive, the American STi has its engine running at lower stress thus it complies with emission regulations. In contrast, the Prodrive does not comply with European type approval thus can only be sold as a tuning kit. 

In other areas, the American STi matches that of the Japanese STi. All the sophisticated hardware are retained, such as the adjustable center differential, 6-speed gearbox, front and rear LSD and Brembo brakes. Subaru is more generous than Mitsubishi.