Rallying rescued Subaru from anonymity and turned the Scooby into a cult car for rally enthusiasts. The lates t
Subaru Impreza WRX STi continues that cult with more power, improved handling and a variable center differential. You can set the torque split to suit dry roads, gravel or rough roads. So you get the benefit of the rallying experience – a good example of motor sport improving the breed, and the image.
Rally specials also available
If you live in the UK, you can also buy special versions of the WRX and STi which pushes the power up to 305 bhp. These are developed by Prodrive, which has been heavily involved in the development of the Subaru World Rally Championship cars.
For compact square-looking sedans, the WRXs are no mean performers: the WRX STi reached 151 mph and sprints to 60 mph in 5.2 seconds. With the 305 bhp kit, the WRX STi can race to 60 mph in only 4.6 seconds, and reach 100 mph in just 12.2 seconds. That’s pretty quick.
As always, the engine of the WRXs is a flat four, coupled to a six-speed manual gearbox and four-wheel drive through a viscous coupling center differential. It was this full-time four-wheel drive, and the car’s compactness, that made the Impreza an ideal basis for a rally car in the first place.
Flat-four engine, 265 bhp
The engine is oversquare with a bore and stroke of 92 x 75 mm to give a displacement of 2.0 liters. For years, Subaru has used aluminum cylinder block and heads, and the 16 valves are operated by twin overhead camshafts with variable valve timing. Hot Imprezas have turbocharging to get the extra power, and the turbo has an intercooler with a water spray to increase cooling when needed.
The WRX develops 225 bhp these days, and the WRX STi pushes out 265 bhp @ 6,000 rpm with peak torque of 253 lb ft (343 Nm) @ 4,000 rpm. You get a good spread of power, not just all that the top thanks to the turbo.
Later models sold in Europe were equipped with the 2.5 liter mill used previously for the US market. The Result: more low-speed power, and better power delivery at any speed.
Improved four-wheel drive with yaw sensor
For the latest models, the four-wheel drive system has between improved. First, you get a yaw rate sensor which detects whether the car is understeering and oversteering, and evidently gives better stability and control. A sort of stability control.
Anther innovation – also found on the Scooby’s deadly rival, the Mitsubishi Evo VIII - is a multi-plate clutch at the center differential which divides torque front to rear according to the setting you choose:
Tarmac
Gravel
or slippery tracks.
There are limited slip differentials at front and rear as well, and the center clutch is designed to make sure there is always plenty of power at the gripping tires. Lack of grip should not be a problem here.
So, you get the traction and cornering power of four-wheel drive, but you can set it to operate how you wish – you don’t have to use it the way they say. Try them all, and see which setting suits your driving style. The choice is between stability or the quick turn-in wanted by enthusiastic drivers.
Improved suspension
Following their experience in rallying, Subaru has also improved the suspension. To start with these increased the stiffness of the suspension pivots and steering rack. Stiff mountings and a stiff body are the start of good handling.
To reduce weight, the suspension arms for the front and rear strut suspension are aluminum, and the feel through the steering has been improved with an increase in castor – up 1.5 degrees, which is quite a big change. A good idea.
To reduce roll, fatter anti-roll bars are fitted, and the struts are inverted, which is said to give less wheel movement in hard cornering. Also significant is a higher rear roll center, which will reduce understeer and roll a little.
All this combined with plenty of rubber in contact with the road: 225/45s 17s with 8 inch rims.
Because the WRX is based on Subaru’s standard body, the car is no lightweight, which is a pity. It weighs 3,525 lb (1,475 kg) ready for the road. That’s almost 600 lb more than the admittedly smaller Golf GTI.
Four-wheel drive should add no more than 150 lb on a car of this size, so here’s another car that needs a weight-loss diet, although the weight is concealed by that great little engine.
Maybe not the prettiest car in its class, and you get a huge spoiler in your rear vision when you buy the STi, but with this performance who cares?
Subaru produced various special versions of this model, and has managed to keep the name in front of enthusiasts, but it was all-change for 2008, with a completely different body style aimed at a different market. Maybe this is the model you want.
