About the Car

It was Mitsubishi who did more than any other manufacturer in the late 1970's to change the way Australians thought about four cylinder cars. At the time the Chrysler Sigma spoiled us with notions of comfort and luxury unheard of in a medium sized package.

So successful was the Sigma, that Mitsubishi was actually able to mount a takeover bid for ailing Chrysler Australia.

In 1981 Mitsubishi Australia made a brave attempt to wring some sporting appeal from its mainstream Sigma sedan, and released the limited edition "Peter Wherrett Special" GH Sigma.

Peter Wherrett was a very influential journalist and driving enthusiast at the time. Wherrett had complained in a review about the handling of the production GH Sigma. Over lunch, Mitsubishi's then Chief Engineer Graeme Longbottom challenged him to do better. "Give me a car and I will," Wherrett retorted.

Mitsubishi then decided to produce a turbocharged edition of the successfull GH Sigma sedan.

In a bold program with turbocharger experts Normalair-Garrett, Mitsubishi produced a limited run of only 500 Sigma Turbos using the relatively upmarket Sigma SE sedan as the platform.

Under the bonnet the Sigma Turbo used the 2.0 litre, SOHC, Astron 4G52 four cylinder equipped with a completely new intake manifold and a Garrett Air Research T03 turbocharger sucking through a Zenith CD 175 carburettor.

Compression was reduced to 7.8:1 with boost running at around 8lb. This increased power from 64.4kW to 116.0kW despite a lack of intercooling or water injection. Driving through a standard 5-speed Borg Warner manual transmission the Sigma Turbo covered the quarter mile in 16.8 seconds and ran to a top speed in excess of 200km/h.

By current standards 116kW and 16.8 secs may not sound like much, but back in 1981 a Holden 308 V8 offered only 10kW more power, while any car that could manage a sub-17 second quarter mile was considered quick.

Externally, the Sigma Turbo was distinguished by its two-tone paint scheme, colour coded mirrors, unique polished 15" Montego alloys, twin bonnet vents for cooling, an aggressive honeycomb or "egg crate" grille and a few Turbo badges.

The car had improved on-road manners thanks to standard four-wheel-disc brakes and a suspension upgrade similar to that from the Peter Wherrett Special. Standard tyres were grippy Pirelli P6s.

The interior was pretty much Sigma SE fare. Seating for five, comfortable honeycomb velour cloth trim, comprehensive instrumentation including a "turbo boost" lamp so the driver could tell when the engine was on positive boost.

Through the late 1970s, the cheapest turbo car on the Australian market was the Saab 900 Turbo. At nearly $30,000 the Saab kept turbocharging technology well beyond the reach of most enthusiasts.

Given its fairly limited production numbers, Mitsubishi priced the Sigma Turbo at just $13,750, undercutting the pricey Saab by more than 50 percent. Mitsubishi saw no need to heavily advertise the car, instead, they sat back and let it's price do the work. It wasn't long before word spread and the 500 Sigma Turbos were snapped up.

The Mitsubishi Sigma Turbo was not only Australia's first locally produced turbocharged car, it showed the market that turbocharging was both viable and a truly affordable performance alternative.