16/09/2026
I always enjoy discovering period road tests of Mazda's classic cars. they offer a fascinating glimpse into how these cars were viewed when brand new.
Here's an article from the reputable Japanese magazine: Car Graphic, July 1975, featuring Mazda's newly released Roadpacer, translated to English......
Mazda Roadpacer AP : Car Graphic “Road Impressions”
Page 44 - Introduction and interior
Mazda Roadpacer AP
C/G Test Group
The opportunity arose to drive Toyo Kogyo’s prestige saloon, the Mazda Roadpacer AP.
The Roadpacer uses the body and suspension components of the Australian GM Holden Premier, imported to Japan in knock down form. Toyo Kogyo then installed its own rotary engine and a JATCO automatic transmission.
It was therefore Toyo Kogyo’s first Japanese market 3 number class large passenger car. The 13B rotary engine is equipped with the REAPS 4 low emission system, making it one of the first domestic cars in its class designed to meet the new Japanese emissions regulations.
The basic body is that of the Holden Premier. Its wheelbase is 2,830 mm, with front and rear tracks of approximately 1,530 mm, and overall dimensions of about 4,580 × 1,885 × 1,465 mm.
On Japanese roads it looks extremely large. The large American style body gives it an imposing presence, although Mazda has made changes to the interior to give it a distinctly Japanese luxury-car character.
It is a four door saloon, and the size of the cabin means that even tall occupants have plenty of room. The rear seat is particularly spacious.
The rear seat is finished in soft beige moquette upholstery, with the same material used on the front seats. The backrest is generously padded and can be adjusted for height and angle. There is also a centre armrest that can be pulled down, giving the rear passengers something approaching a chauffeur driven luxury car experience.
The seat material also helps prevent passengers sliding sideways when cornering.
The rear compartment has its own air conditioning/cooling system, with controls for the blower, the AM/FM stereo, front/rear speaker balance, rear cigarette lighter and reading lights incorporated into the rear quarter pillars. There are also power window controls for the rear passengers.
In other words, the rear passenger has an impressive degree of control and comfort.
The tester says that the feeling of “peace” and luxury offered by the Roadpacer isn't simply due to the seats and equipment. Its soft ride and low noise level are equally important.
Page 45 - Suspension, ride and the 13B
The Roadpacer's suspension is fundamentally based on the Holden system.
At the front it uses double wishbones and coil springs.
At the rear there are two longitudinal lower arms together with a Panhard rod, forming a four-link arrangement to locate the live rear axle. The rear axle is rigid, with coil springs.
However, Toyo Kogyo modified the suspension to suit its own requirements. The coil springs are softer than those of the Holden Premier, and a front stabiliser/anti-roll bar has been added.
The result is an exceptionally soft ride.
Most road irregularities are absorbed before they reach the occupants, with sharp impacts considerably reduced. The tester describes the Roadpacer as floating along almost like a large American car, with a gentle “floating” movement.
The tyres are large 7.50 -14 4PR cross-ply tyres, and although their construction contributes to the soft character, road noise is surprisingly well suppressed.
Even at around 100 km/h on the Tomei Expressway, the cabin remains remarkably quiet. The tester notes that the speedometer itself reads about 8% optimistically, something worth remembering when interpreting the road test speeds.
At 100 km/h the sounds entering the cabin consist mainly of the rotary engine turning at around 4,000 rpm, wind noise and the windscreen wipers. Even so, conversation can be carried on in a normal voice.
The rotary's inherently low noise level, together with the substantial sound insulation in the body, makes the engine surprisingly unobtrusive except during hard acceleration.
The engine
The Roadpacer uses Toyo Kogyo's largest rotary engine at the time:
13B, 654 cc × 2 rotors
The basic engine is related to the unit used in the Luce Grand Turismo and Cosmo, but the port timing has been altered to increase torque at low and medium engine speeds.
The specification given in the article is:
Compression ratio: 9.4:1
Carburettor: four-barrel
Power: 135 PS at 6,000 rpm
Torque: 19.0 kg-m at 4,000 rpm
Transmission: JATCO 3-speed automatic
Kerb weight: approximately 1,575 kg
And this last figure is important to the tester.
The Roadpacer is considerably heavier than the rotary-powered cars Mazda was accustomed to producing.
The article points out that a Century or President of roughly 1,800 kg has a larger and more powerful engine, while the Roadpacer has only 135 PS. Consequently, the car doesn't feel particularly lively.
For normal city driving and expressway speeds around 100 km/h, however, the lack of power isn't a serious problem.
Automatic transmission and performance
The JATCO automatic has ratios of approximately:
2.458 / 1.458 / 1.000
In D, full throttle allows approximately:
1st: 60 km/h
2nd: 105 km/h
If manually selected, the corresponding speeds increase to approximately:
1st: 70 km/h
2nd: 125 km/h
The D to 2 kickdown remains available even at speeds above about 90 km/h, which is useful for overtaking on the highway.
The tester says that on an expressway there is therefore little difficulty in finding enough performance for an overtake.
But things change dramatically on mountain roads.
Here the 1,575 kg weight becomes much more apparent. The Roadpacer has only 135 PS, and compared with lighter cars the power to weight ratio is not impressive.
The automatic's behaviour also becomes frustrating.
When climbing a hill, selecting 2nd can produce useful engine braking and prevent excessive shifting. But if speed falls entering a corner, the transmission can shift down automatically. Alternatively, selecting D and applying full throttle causes a kickdown to 1st, producing the characteristic high pitched rotary “whoosh” and the acceleration needed to get out of the corner.
However, once the driver eases off the throttle, the transmission automatically shifts back through 2nd and into D, and the car once again feels short of power.
The tester essentially says that there are two ways of driving it on hills:
Select 2nd and climb slowly, accepting the low speed; or
Keep it in D and use full throttle, allowing the automatic to repeatedly shift up and down.
Neither is particularly elegant.
The first method is considered more appropriate to the Roadpacer's character, but it requires patience.
Steering and handling
Despite its huge size, the Roadpacer's steering is described as surprisingly direct.
It has power assistance, but the tester finds it somewhat firmer and more communicative than the steering of a Crown Royal Saloon.
The variable steering ratio is approximately 17.5 :11.0, and there are only 2.6 turns lock to lock.
The minimum turning radius is 5.7 metres, roughly the same as a Toyota Century and only about 0.1 m greater than the Nissan President.
Because the steering is relatively quick for such a large car, the tester warns that an unconscious or abrupt steering input can make the large body roll noticeably.
It therefore takes some familiarisation to drive the Roadpacer smoothly.
On the other hand, the steering has good self-centring action, so the driver doesn't have to constantly make large corrections.
The soft suspension remains a major advantage for comfort, although the tester acknowledges that this softness contributes to the Roadpacer's tendency to lean in corners.
Page 46 - More equipment, luxury and final assessment
The Roadpacer's large body and soft suspension contribute greatly to its luxury-car character.
The tester comments that the body is a proper monocoque structure, rather than feeling like the separate frame American cars of the period. Even over poor surfaces there is little of the squeaking and body flex sometimes associated with large American cars.
The brakes use front ventilated discs and rear drums, and the car remains stable under braking.
The fuel consumption during the test was approximately:
5.00 km/litre at an average speed of about 100 km/h
(or roughly 20 L/100 km).
The tester notes that this is not surprising considering the car's weight, automatic transmission and rotary engine.
The fuel tank holds approximately 75 litres.
Interior equipment
The Roadpacer was clearly intended to compete with the top Japanese luxury cars.
The test car had:
Front bucket seats
Separate rear seat
Adjustable seat-back angle
Power steering
Power windows
Remote control electric door mirrors
AM/FM stereo
Cassette-type car stereo
Rear-seat air conditioning/cooling
Rear reading lights
Rear cigarette lighter
Rear window demister
Central locking
Power window safety controls
Electric boot/trunk release
Headlight dip switch operated from the floor
The article points out that some of these features were becoming standard equipment on American cars, but Mazda had incorporated them into the Roadpacer as part of its prestige-car specification.
The power window switches, for example, are designed so that the driver has control over them to help prevent accidents involving children.
Price and competitors
The Roadpacer AP cost approximately:
3.68 million yen
for the separate seat specification.
The article compares it with other Japanese prestige cars:
Toyota Century: ¥3.176–3.420 million
Nissan President: ¥3.328–4.078 million
Isuzu Statesman de Ville: ¥3.480 million
Mitsubishi Chrysler: about ¥3.180 million
The tester therefore concludes that the Roadpacer isn't especially cheap compared with its rivals.
However, it has one significant advantage: the REAPS 4 rotary engine requires less maintenance than the V8 engines fitted to many of its rivals.
