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Supercharged Rex

We check out the Japanese-market Subaru Rex - with supercharger!

By Michael Knowling

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At a glance...

  • Japanese-market Subaru Rex import
  • 550cc supercharged
  • Sliding roof model
  • Cheap as!
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When talk turns to factory supercharged vehicles, the list of cars is pretty short – there’s the Eunos 800M, Jaguar XJ-R, Mini Cooper, Holden Commodore/Statesman, a pair of US-market Ford V8s, a handful of Japanese-market Toyotas, some Daimler chrysler models - and little else.

Oh, and don’t forget the mighty Japanese-market Subaru Rex Supercharger!

Released in Japan during 1989, the Rex is one of the most intriguing ‘Kei’ class econo-midgets – it’s the only one to use a supercharger rather than a turbocharger for forced induction.

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The Rex’s 550cc 4 cylinder motor (coded EN05) employs a tiny Roots-type positive displacement supercharger to deliver ‘big engine’ driveability and torque. The mechanical platform is pretty basic – only a SOHC head, a relatively simple fuel injection system and 8.5:1 static compression ratio. But add that diminutive supercharger and a top-mount air-to-air intercooler and you’re talking 45kW at 6400 rpm and 75Nm of torque at 4400 rpm. This compares closely with the contemporary 550cc Daihatsu Mira EFI turbo (see Mira, Mira Off the Wall ) and Suzuki Alto Works (see Wicked Alto Works).

The advantage of the supercharger approach is the generous amount of low rpm torque, part-throttle performance and throttle response at your disposal. But, really, the supercharged Rex doesn’t feel much more responsive than turbocharged Kei class models (which use extremely fast-spooling turbos). The supercharged engine also makes some curious sounds – a whirring noise under load at low/mid rpm building to a wail at high revs. The engine feels happiest when spinning at about 3500 to 6800 rpm (800 rpm shy of redline).

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Weighing around 660kg in slide-back roof form (as tested), the supercharged front-wheel-drive Rex should be capable of accelerating to 100 km/h in around 12 seconds or less. (We were unable to test the performance of our test vehicle due to poor condition tyres and worn gearbox synchros.) But we can tell you this in an easy beast to launch – no need for a high rpm clutch dump.

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Note that a 4WD version of the supercharged Rex was offered in Japan. These 4WD versions have an E-KH2 chassis code, while the front-drive versions have an E-KH1 code. A 5-speed manual was the most popular gearbox choice but a CVT auto was also offered (CVT being a pretty high-tech feature for the late ‘80s).

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Tiny ventilated discs can be found at the front while the rear employs drum brakes - the brake pedal is light and progressive. Strut suspension is found at the front and a trailing arm IRS lives at the opposite end. We expected the Rex to provide good stability over rough road surfaces, but the dampers on our test vehicle were so worn it was impossible to tell... The front-wheel-drive version is also a determined understeerer – at least with the poor condition 155/70 12 tyres on our test example. The non-assisted steering also loads up during tight manoeuvres.

But the supercharged Rex holds another important ace up its sleeve – an oh-so-cool electric slide-back roof, which was a factory-fitted option.

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On sunny days when the birds are singing you can slide back the Rex’s fabric roof to enjoy wind-in-your-hair motoring. And a single open/close button is all it takes – no need to fumble around with levers and locks. When the weather is less favourable, the fabric roof folds back into place and doesn’t consume any interior space.

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Other interior equipment includes air conditioning, a supercharger boost light, tacho, sports trim and relatively supportive seats. Space utilisation is excellent and there’s useable seating for 4 - no problems in terms of head room or rear passenger knee room, but don’t be alarmed when you start rubbing shoulders with the person seated next to you... Rear cargo space is limited with the rear seat in its normal position, but the split rear backrest can be folded forward if required.

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Visually, the supercharged Rex receives more than a few second glances. Its slide-back roof isn’t what you’d expect in such a small vehicle - nor is the bonnet scoop, sports bumpers, skirts, twin exhaust tips, rear spoiler or fog lights... Oh, and check out the 12 inch alloys – a downsized version of Subaru Liberty (Legacy) RS turbo wheels.

Very cute!

The supercharged Rex tested here is currently available through Adelaide’s With 95,000km on the odometer, you’d give this machine some detailing and maintenance work it would scrub up all right. And the cost? Just AUD$3000 non-ARD’d.

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Once you get this puppy registered and driving on the road we reckon it’d be good fun to play around with the exhaust, air intake and intercooler. You might also look at upping the boost pressure. But be aware that you don’t want to break the engine – the Subaru 550cc engine is an orphan in Australia. Most body parts appear interchangeable with the Australian-market 1989 Subaru Sherpa, but local versions came with only a naturally aspirated carby engine.

It might not be a drag racing machine, but for AUD$3000 the Subaru Rex is a cheap entry into the supercharged club!


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