Mitsubishi Sigma

Introduction

Key to the success of the Sigma was the combination of very good marketing, support from the media and a good basic car with a range of models from which to chose. It quickly established itself as a class leader – and it was up against some formidable competition, including Datsun's 200B, Toyota’s Corona, Ford's Cortina 4, Holden’s Sunbird and Mazda's Capella. What stood out on the Sigma was the smooth performance - remarkably fast, but with good acceleration, especially in the 2 litre Astron versions.

At its introduction in late 1977 the Sigma was the same car that was made and sold in Japan, but attention to customer feedback enabled Mitsubishi to tailor the Sigma for local conditions. Inside and out, the range underwent significant improvement over the years. The Sigma offered a good ride, acceptable handling, reasonable road holding and braking, plus very good internal layout and appointments. The drawback was the steering – which followed the usual Japanese formula of recirculating ball – which always provided a "woolly" centre feel.

Main driving controls were on steering column stalks, while others for heater etc were mounted in the centre of the facia. The moulded centre console had plenty of indentations for carrying odds and ends, plus there was a moulded tray atop the passenger side facia, plus a deep parcel tray above the passenger foot well, and a box like pocket at the front of the centre console.

The boot space was good for a two litre. Cloth seating and high quality carpeting made the interior inviting, without putting the GL on the same level as the more luxuriously appointed SE. The driver's seating position provided a good measure of all round visibility, with only a narrow arc of vision shielded by the fairly substantial "C" pillars to the rear. Accommodation for four was very good with a fifth passenger space available for all but the longest of trips.

The Astron Engine

Like most Japanese units, the "Silent Shaft" Astron engine was anything but when first started up in the morning. It had a unique whirring noise, associated with chains driving the two balance shafts - and the noise was always present, although thankfully it got quieter as the motor warmed up. The whole engine was much less obtrusive after two or 3 minutes, but many were left scratching their heads wondering what the silent-shaft moniker was referring to. Perhaps it should have been called a smooth shaft. Or better still, maybe the word shaft was not appropriate at all.

Smoothness was the real key to the Sigma's luxury feel. The gearbox was a gem, and if you were punting it hard the slick change from second into third was brilliant – although you had to be careful not to accidentally go from second to fifth. Once mastered you would realise what a delightful box it was. Fifth gear was never really required around town, unless you were trying to be super economy conscious, but on the open road it cut the revs by about 500 and which made for quieter and more economical cruising.

With such a free spinning engine as the Astron, it was easy to use low speed performance for rapid transit through towns. A big depression of the throttle brought in the carby's second choke and release a reserve of power. At higher speeds, quite naturally in a two litre, acceleration would die away a little, as aerodynamic effects took over. However, there was ample enough power left to give assistance through fast corners. And in any case, failing that, there was always the lift off throttle procedure to help tuck the nose in if all else fails.

The original Sigma’s tended toward understeer that required positive action to achieve some measure of oversteer, at medium to high speeds. By 1979 that had changed to an initial reticence to commence a direction change, but then there was a roll movement that brought in a mild oversteer situation. Obviously the Mitsubishi engineers had tweaked the suspension settings during manufacture – most probably a slight alteration to the rear springing and damping. Lifting off the throttle would simply accentuate oversteer.

On gravel it was much the same story, only there it made for even more fun driving, as the car could be thrown around with abandon, still remaining under control. Road holding was generally good for the performance speeds available, but it was hard to maintain a constant line throughout a long corner. Corrections were necessary to stay on line although there weren't any difficult changes of basic handling properties (understeer to oversteer and back or vice versa) to upset stability. In the wet the Goodyear Supersteel radials were a little tricky - they'd cling on quite well, but the limit tended could be found all too quickly with any warning.

The brakes were good too – although the pedal pressure was arguably a little too soft. Nevertheless it provided a progressive feel, especially when the lock up situation was getting close. The Sigma may not have been as economical as today’s cars – but it was still very respectable. Around town owners claimed better than 11 litres per 100 km (26.1 mpg) , and 30 mpg was possible in the country. Performance wise, the Astron took 18.7 seconds for the standing 400 metres and 12.5 seconds from zero to 100 km/h.

The Sigma Sports Pack

The Sigma sports pack was released in 1979 and consisted of show gear more than go gear. There was sports instrumentation, with tacho and a set of fairly poorly calibrated gauges. There was a soft feel sports steering wheel, quartz halogen headlights and steel radial tyres, together with black painted door tops and sports striping. If you really wanted your Sigma to be a show-pony, for an extra $227 you could option alloy wheels, a five speed gearbox and the two litre Astron engine – well worth the money.

A nice touch with the Sigma was the feeling that the sports pack really belonged to the car - rather than being simply an assembly of bits and pieces. This was aided by the one piece headlining inside and the facia which looked as though it was designed by one person rather than a committee. The GL featured reclining front seats, but not the height adjustment of the SE. All Sigmas had the variable rake steering column, and this was always an asset to getting comfortable, although at its lowest setting it did obscure the speedometer to some extent.

At a basic $5918 in 1979 Chrysler's Sigma GL was good value, a fact proven by the speed with which dealers were able to move whatever stocks they had. By mid 1979 Chrysler was approaching 85% local content with the model, but production capacity was restricted, so demand always exceeded supply in the early years. Adding the Sigma wagon to the range was a stroke of genius - Chrysler's timing being perfect. This provided a gap filler for the last hole in the line-up, launched at precisely the right time when more and more people were looking for smaller, more economical wagons.

Car of the Year

The 4th generation model released in 1980 represented the most significant improvements for Australian conditions – it even taking out the Car of the Year award in New Zealand. The basic model was the 1.6-litre Sigma, then the GL and SE which came fitted with a 2.0 litre Astron and the optional 2.6 litre. There was also a five-speed manual version of the 2.6 litre available. Outside there was a new black plastic grille, and Falcon-style bumpers, Scorpion-style dual quartz halogen rectangular headlights, and new tail lights provided a more aggressive and upmarket look.

Changes to the sheet metal gave the car a 'flat-nose' look. Inside, square dials replaced the previous models round ones, and the dashboards were colour-coded. The top of the line SE now also featured a digital clock, stereo tape deck, and a fuel-pacer light on the bonnet as standard. One of the most common complaints about the earlier Sigmas was directed at the handling and steering response. A major rebuild of the steering box reduced by 35 per cent the amount of steering-wheel movement required for any manoeuvre. Sloppiness had finally been eradicated, but unfortunately so was any real feel for the road; however, it is an acceptable compromise.

The front and rear springs were variable rate; that is, in driver only situations the springs were softer than on previous models while under load the spring rate increased and stiffened up the ride. This also helped reduce front-end dive under heavy braking. A substantial increase in pad area and disc diameter has likewise improved the braking; and economy was further enhanced by changed differential ratios and a taller wheel-tyre combination.

Some of the changes could be questioned on grounds of taste, such as the square dials or the thin steering wheel, but there was indeed little argument from the consumers. Ultimately it was the 4th generation Sigma that was thoroughly sorted for Australian conditions, and this made it a much better car than its predecessors.