Mitsubishi Colt Galant AII GS (1970)
Publication: Car Graphic
Format: Road Test
Date: March 1970
Author: “C/G Test Group” (uncredited)
Summary: High performance version of the Galant, SOHC 1.5-liter engine, revs smoothly up to over 7000rpm, extremely responsive across the entire range, exceptional fuel economy, variable ratio steering with good response, handling generally excellent, but tends to oversteer early on standard tires, good value for money.
Road testing the Mitsubishi Colt Galant AII GS
In December of last year, Mitsubishi Heavy Industries made a bold entry into the 1300-1600cc class, which is not only the most competitive segment of the domestic market, but also one of the most hotly contested markets internationally. Its strategic model for this challenge, the Colt Galant, got off to an auspicious start, recording sales of 6,400 units in the month after its release.
The Galant is available in two models, the AI with a 1.3-liter engine and the AII with a 1.5-liter engine, both with a shared four-door sedan body, and is further divided into seven variations with minor differences in specifications. The car we tested was the AII GS (Grand Sport), which is positioned as the high-performance sports sedan model of the Galant line, and is also the most expensive (711,000 yen).
To state our conclusion at the outset, we were deeply impressed by the high dynamic standard and overall refined behavior of the GS. Although the catalog data for domestic cars tends to be very optimistic in our long experience, this Galant GS nearly matched all the figures listed in the catalog in our testing. For example, its top speed averaged 173.1km/h (catalog figure: 175km/h) over the 1km section of Yatabe, and its 0-400m acceleration time was 17.2 seconds (16.9 seconds) while carrying nearly a full load. Moreover, constant-speed fuel economy was remarkable: 19.2km/l at 60km/h, and 12.8km/l at 100km/h.
With the exception of fuel economy, such figures have little practical meaning in the case of passenger cars. However, they at least serve as evidence of minimal manufacturing variation between individual cars, and Mitsubishi’s policy of publishing conservative catalog figures inspires considerable goodwill.
The key to the GS’s performance undoubtedly lies in its excellent engine, so let us begin with an overview of its specifications. The Galant’s power unit is an entirely new SOHC design, unrelated to that of the previous Colt. While conventional in its basic layout, it incorporates a number of ingenious refinements in detail, and as a result achieves a very high level of performance. Indeed, this approach of intelligent, incremental development appears to be a policy that has been followed throughout the car’s design.
The most distinctive feature of the Galant engine is the highly efficient design of its intake and exhaust systems. The aluminum-alloy SOHC cylinder head has been given an almost perfectly hemispherical combustion chamber, with large-diameter intake and exhaust valves arranged opposite one another at an angle of approximately 47 degrees. The intake ports are given a slight twist relative to the combustion chamber, inducing swirl to improve combustion efficiency.
In the case of the 1499cc AII engine, bore and stroke dimensions are 74.5 × 86mm, making it a decidedly long-stroke design. This ratio, we are told, was chosen primarily to reduce the diameter of the combustion chamber’s base relative to its depth, forming an ideal domed shape.
Both the output and torque figures are well above the standards of this class. Even the standard AII, with a compression ratio of 9.0 and a single Stromberg carburetor, produces 95ps/6300rpm, while the GS, with a compression ratio of 10.0 and twin SU carburetors, produces 105ps/6700rpm. Torque is also strong, with the standard model delivering 13.2kgm/4000rpm and the GS delivering 13.4kgm/4800rpm.
The chassis design is entirely orthodox, but here again, modern thinking is applied in the details. The overall body size corresponds roughly to the Nissan Bluebird, but the AII GS weighs only 855kg, some 75kg lighter than the Bluebird 1600 SSS. The front suspension is the MacPherson strut layout that has become standard for compact cars, but the lower arms are a substantial pressed wishbone type, and the spacing between the rubber bushings at the body mounting points is set wide apart. As a result, changes in suspension geometry are minimized, promising both accurate steering and effective isolation of road noise. At the rear, the rigid axle is suspended by two equal-length leaf springs.
The brakes are common across all AII models, consisting of 9-inch front discs and 8-inch rear drums with automatic adjustment, arranged in a dual-circuit system. AII models are fitted with 4J x 13 rims and 6.15-13 low-profile tires.
According to Mitsubishi Heavy Industries, the suspension settings are the same for all Galant models. However, when we compared the tested AII GS with the AI Custom we purchased for our long-term evaluation, we found that there are fairly significant differences. The manufacturer attributed these to the difference in tires (the GS we tested had Bridgestone Skyway HHT Nylon 4PR tires, while the C/G AI Custom has Yokohama Nylon 4PRs), but there is at least one other substantial difference, in that the GS’s ride height is 15mm lower.
Once on the road, the first impression is of the engine’s remarkable smoothness as it revs up to high rpm. The tachometer shows 6400-6750rpm as the yellow zone and 6750-8000rpm as the red, but in the lower gears the engine revs up to 7000rpm with ease. From its 800rpm idle to the practical maximum of over 7000rpm, it is extraordinarily smooth for a four-cylinder reciprocating engine–so much so that among domestic cars, even six-cylinder units offer no clear superiority.
With 105ps and a vehicle weight of 855kg, performance is more than adequate. Moreover, thanks to the engine’s flat torque characteristics, one can run quietly and briskly in city traffic without exceeding 2500rpm. For the same reason, throttle response is always crisp and immediate in any gear. If we had to define a particularly effective operating range, it would be between 3000 and 6500rpm.
Especially noteworthy is the engine’s excellent extension at higher speeds above 5000rpm, where it far surpasses the single-carburetor AI we tested at the same time (though, as noted in the AI report, its 1300cc engine also revs unusually well for its class). Mechanical noise from the engine itself is low, and because the cooling fan uses a fluid coupling, fan noise is well suppressed (the AI’s fan is driven directly and sounds somewhat harsh at high speeds).
It is therefore unfortunate that the exhaust system transmits a fair amount of resonance into the cabin, becoming quite strong right around 3500rpm. This corresponds to around 90-100km/h in top gear, which is exactly the range that is usually sustained for long periods on the expressway.
The gear ratios are well-matched to the engine’s output. For the top speed test, the car was driven flat-out continuously on the 5.5km Yatabe circuit, with average speeds recorded over both the 1km straight section and a full lap of the circuit. Under ideal, windless conditions, the GS recorded an average of 173.1km/h on the 1km section. Engine speed at that time was about 6200rpm, 200rpm below the yellow zone, giving the impression of ample reserve.
In Japan, top speed figures have little practical significance. In foreign markets, however, where the Galant will soon be released, it is not uncommon for cars to be driven flat-out for hours at a time. Our impression is that the GS’s practical cruising speed is high, and it should be capable of maintaining 160km/h for extended periods.
It should be noted that the test car’s speedometer was, unusually for a domestic vehicle, pessimistic rather than optimistic. It indicated 100km/h when the actual speed was 104km/h, and 160km/h at an actual 167km/h. Those inclined to drive at high speeds should exercise caution.
The appropriate spacing of the 4-speed gearbox ratios became especially evident during acceleration testing. When shifting up at 7000rpm, engine speed drops to approximately 5000rpm–very close to the 4800rpm torque peak–placing the engine in the ideal range for continued acceleration in the next gear. Third gear, which extends up to roughly 140km/h at the start of the red zone (6750rpm), is especially well suited to quick overtaking on the highway.
To illustrate the power reserve, the top-gear overtaking acceleration figures for 40-80km/h, 60-100km/h, and 80-120km/h were 9.7 seconds, 9.4 seconds, and 10.7 seconds, respectively. These times are surprisingly close to those of the Corona Mark II 1900GSS, which has a substantially superior power-to-weight ratio (7.5kg/ps, compared to the GS’s 8.1kg/ps).
The gearshift has a good feel, with light and positive operation. The test car exhibited weak third-gear synchronization, and above 5000rpm the gearbox shaft produced abnormal vibration accompanied by intrusive noise. However, the C/G AI Custom and other Galants we have tested previously had no such problems, and their synchromesh proved extremely robust. As a result, we believe this was a problem specific to the test vehicle–which had already covered more than 6,500km, and may have been subjected to particularly hard use.
The clutch is light, with an appropriate pedal stroke, and even when released abruptly from high engine speeds, as during acceleration testing, there is very little slip and engagement remains smooth.
In short, despite its high level of performance, the Galant AII GS is remarkably easy to drive. Even a complete novice driving in city traffic for the first time would likely find it entirely manageable.
One morning during the test period, outside temperatures fell to -6°C. Under such conditions, it took two or three attempts at cranking to start the engine. However, because the intake manifold is pre-heated with hot water, it warms up extremely quickly. After starting, if we allowed the engine to run for about one minute and then released the choke, the car could be driven away immediately with the usual smoothness (although it took some 12-13 minutes for the water temperature needle to reach the normal reading).
As mentioned earlier, one of the most pleasant surprises of the GS was finding that its high performance is matched by exceptionally good fuel economy. Constant-speed fuel consumption tests (conducted over a 1km section at a steady speed) produced almost unbelievable figures: 20.8km/l at 40km/h and 16.6km/l at 80km/h. Indeed, these results were superior even to those of the C/G AI Custom tested at the same time (the AI recording 17.8km/l and 14.7km/l at the same speeds).
Possible explanations are that the AI is geared slightly lower (speeds per 1000rpm in top gear are 27.1km/h for the AII, 24.0km/h for the AI), and that whereas the C/G AI has been driven only 2,000km, the tested AII’s engine had already run some 6,500km, and was presumably freer of internal friction. In real-world driving, however, where acceleration and deceleration are frequent, the results did not mirror the steady-speed figures. Over a total test distance of about 440km (including roughly 200km at the Yatabe test course) under identical conditions, the AI averaged 9.21km/l, while the AII GS returned 8.32km/l. With a 45-liter fuel tank, this still permits at least 500km of range at a steady 100km/h on the highway. In any case, the AII GS is decidedly economical in view of its performance.
The brakes are appropriate to the car’s speed capability. Deceleration of 0.95g was achieved with 35kg of pedal effort, which is reasonable and does not suggest the need for servo assistance. Nose dive is minimal. In the 0-100-0 fade test, pedal effort increased from 20kg on the first stop to 27kg on the seventh, and the braking feel became slightly rougher; even so, by the tenth stop the pedal effort had only increased to 30kg, so it can be said that the brakes offer satisfactory fade resistance. It is also worth noting that the relative positions of the brake and throttle pedals make them well suited to heel-and-toe.
Despite its conventional suspension layout, the handling is at a fairly high level. The ball-and-nut steering uses a variable ratio–sharp at 15.6:1 near the straight-ahead position, increasing to 18.2:1 toward full lock–and offers what might be described as a fluid, well-damped feel, with moderate, natural weighting. Response is considerably sharper in the GS than in the AI, though not excessively so. Since the steering ratios are identical, this difference can be attributed mainly to the difference in tires. The test car’s Bridgestone Skyway H tires, though only four-ply (4PR), felt relatively stiff, with high lateral rigidity.
At normal speeds the car exhibits very mild understeer, faithfully following steering inputs. Body roll is surprisingly limited for a relatively tall car. However, ultimate adhesion from the tires is not especially high, and the rear wheels break away sooner than expected, leading to oversteer. Because roll is so well controlled, this initial transition can be somewhat surprising. Once accustomed to it, however, the driver can use this tendency consciously, modulating the throttle to slide the tail and tighten the line through sharp corners.
While driving through the mountains, we attempted some rally-style driving on a winding, rough-surfaced forest road. Even with standard suspension, the GS was able to maintain fairly high speeds. Over a distance of 7-8km, we repeated a sequence of hard braking before each corner, balancing steering and throttle to swing the tail, accelerating at full power along the short intervening straights, and braking sharply again. In such conditions, the quick steering and dependable brakes proved invaluable. The accompanying AI Custom was, as expected, less suited to this type of driving; its stronger understeer and all-drum brakes inspired significantly less confidence. With firmer suspension settings and radial tires, the AII GS would have genuine potential as an excellent rally car–its power is already more than sufficient.
If we could make one suggestion to improve the suspension, it would be to add a torque rod at the rear. Because of the relatively soft setup and ample power, abrupt starts during acceleration testing tended to provoke wild axle tramp.
Ride comfort differs markedly between the front and rear seats. The front seats are generously sized and comfortable, and proved extremely satisfactory over all kinds of road surfaces. Even after nearly ten hours of driving in a day, we were not overly fatigued. Lateral support, in particular, is better in the GS than in the AI. The rear seat is dimensionally spacious, but because of the firm damping, sharp vertical movements are transmitted rather strongly over poor surfaces.
Since the interior is mostly shared with the AI, we will leave the details to that report and focus on the features specific to the AII GS. The driving position is excellent. The wood-rimmed steering wheel can be adjusted up and down by about 50mm–one of the Colt’s characteristic features–so it can accommodate drivers of almost any build. Our only complaint regarding the controls is that the horn button is located in the center of the steering wheel. During the rally-style driving described above, the need to remove our hands from the wheel rim to sound the horn proved inconvenient (in this respect, the AI Custom, with horn buttons embedded in the spokes, is better).
In summary, the AII GS is a vehicle that serves admirably as everyday transportation, is well suited to sporty hard driving, and should almost completely satisfy the family man who wants one car capable of doing everything. Within this class, it may fairly be called “best value for money.”
Postscript: Story Photos
