Road Test: Mazda RX7
Dynamic flair
When your host tells you to bring shorts and wellingtons, it is a fair bet that it will be the latter which are needed most, and inevitably the rain was persistent throughout my first visit to Cornwall. But from our base at Harlyn Bay we were able to tackle with confidence everything from tiny lanes to moorland dual-carriageway with the surefooted help of Mazcla’s latest version of the rotary-engined RX7.
I was very fond of the previous RX7, but it was really too small all round to carry everyday cargo. But the new car steps up a grade— it is a bigger car, with more power, and all the advances that large investments in computer time bring, particularly what Mazda calls Dynamic Tracking Suspension. At 150 bhp the RX7 with its twin-rotor engine is squarely in the class of the Porsche 924S, and the company is open about its intention to achieve conquest sales at the expense of the German marque. Since the RX7’s price was fixed, the fluctuations of the Deutschmark have pushed the prices of German machinery steadily upwards, to the undoubted delight of Mazda (UK). But can a manufacturer of middle of the road family cars seriously compete in the area of prestige engineering?
For once the “new car” claim is completely justified, from the new smooth curves of the exterior, through the reactive g-sensitive suspension, the plush interior with its fancy seats, and a much superior steering set-up, to an engine of much increased performance— although truth to tell the power unit is new only to these shores. Japanese and American customers have been able to enjoy this 150 bhp twin-rotor installation, known as the 13B, for two years past, but of course in the older RX7 such an engine was perhaps stretching the chassis somewhat. Now this hearty and responsive little motor has a truly suitable home.
Despite the very small number of rotary engines actually sold in this, the only Wankel-powered vehicle still in production, Mazda has continued with steady development: apart from the now-expected electronic fuel injection and engine management, the 13B benefits from the six-port induction which first appeared on the 13A in 1985; this is the rotary equivalent of the four-valve head, sucking the fuel/air mixture in through two ports per chamber instead of one.
With twin spark-plugs firing each chamber in turn at its most compressed, it is hard to make direct size comparisons between the rotary and the reciprocating engines. With the former’s three power-strokes per revolution, it is not unfair to triple the single chamber volume of 654cc, equating each rotor to just under two-litres. Viewed as a 3.9, 150 bhp would look mediocre, but from a 1300, it is more than healthy.
Torque is not quite as strong, but it does peak at 3000 rpm (134.5 lb ft), and the eagerness of the engine to whistle up to the crest of the power curve (6,500 rpm) combined with a fast gearchange makes this a delightful and responsive combination. One of the main advantages of the rotary engine is its small size: it is the size and shape of a lorry gearbox, and Mazda has set the alloy crank-case exceptionally low and far back, resulting in a weight distribution of almost exactly 50/50 without resorting to a rear transaxle.
Aluminium A-arms locate the bottom ends of the front struts, and dual-compliance bushes absorb fore-and-aft shocks while minimising lateral movement. But behind, things get even cleverer: deliberate small amounts of rear-wheel steering are introduced under carefully-controlled circumstances, with the aim of getting the best of all worlds. Like the Weissach axle the Porsche 928S, the outside wheel is made to point inwards no matter what provocation is brought to bear on it (braking, acceleration, or neutral cornering), thus countering any incipient slide or spin. But during the first moments of turning in to the bend, the wheel actually toes-out slightly, giving the sort of sharp steering response which sportscars ought to demonstrate; as lateral forces rise to about 0.4 to 0.5g, the patented Triaxial Floating Hub begins to switch to toe-in instead, stabilising the vehicle.
My first experience of this system was on the Vallelunga circuit in Italy, and at the time I felt that overall result was too much understeer. But a race-track is a cruel experience for most road cars, amplifying harmless characteristics to a noticeable degree; so having already criticised the RX7 in Motor Sport for a reluctance to turn corners on super-sticky tarmac at punishing speeds, I have now to report that in more realistic surroundings on British roads, the chassis is not only grippy and well-balanced, but very predictable. It does have the intended effortless turn-in, and the transition from toe-out to toe-in, while quite apparent to the driver, is perfectly smooth.
Theory would suggest some quirky effects if the tyre were made to slide: would the sudden reduction in lateral force introduce toe-out, exaggerating the situation, Well, while the impressive grip of the Bridgestone Potenza unidirectional tyre can be overcome by excessive throttle in the damp, the resulting slides are as dainty and controllable as on any live-axle car, brought to heel in a second with a slight twist of the wheel.
Like its predecessor, this is a 2 + 2 hatchback, though with more headroom behind than before, allied to a larger load-space and opening. A neat vertical well stores the thin spare tyre right in the tail, leaving a flat floor with two luggage straps, spoilt only by the tall suspension turrets for the coil-springs which act on the twin-link trailing arms. Large speakers forming flat tops help to disguise these. Drop the shallow backs of the rear seats and the goods platform extends another 18in or so, adding flexibility, although the space is actually rather more usable with the seats up. Belts are fitted for rear passengers, but due to the lack of space, their upper anchorages are only some six inches behind those for the front occupants.
Comments have been made about the Porsche-like nose of the new body shape, but that comparison is not as well-founded as the rear-end’s similarity to that of the Chevrolet Camaro. But derivative or not, this bigger shell looks more masculine with its wheelarch blisters, altogether more aggressive than the rather petite shape of the last one.
Deformable GRP-reinforced urethane forms the rounded front bumper/spoiler assembly, and Mazda has cleverly enabled the pop-up lights to be flashed while down: the lamps remain vertical when retracted, and a narrow window in the bumper allows the flash to be seen. Flush glass, scalloped wheelarches, sill mouldings and a small rubber lip on the tail make for a drag co-efficient of 0.30, despite the wide 205/60 tyres, and the large wrap-around window which forms the hatch has a narrow black surround to bleed it smoothly with the shell.
Visually, the character of the old model, emphasising the B-post, has been retained, though with less bonnet and more cabin. But three-quarter vision is seriously affected — that rear pillar looks twice as wide from within.
Internally, the styling is restrained, with a plain dash incorporating a large central tachometer, slightly smaller speedometer to its right, and subsidiary gauges to the left; the largish wheel allows a good view of the revs, but I lost the top comers of the panel when the adjustable wheel was in a comfortable position for me. The projecting surround incorporates large fore-and-aft wheels for wipe/wash on the left (two-speed plus variable intermittent) and lights on the right, with push-buttons for foglamps, flashers, heated rear window, plus a dash rheostat, let into the sides.
It all works perfectly well, though I do not feel it has any advantage over using two or three stalks instead of the single off-side lever that Mazda provides for indicators, dip and flash. Warning lights are recessed in a row along the dash-top, rather out of eyeline, and below this a squarish console contains ashtray and lighter at the bottom (when will manufacturers junk the accessories of this nasty habit and replace them with a useful rubbish bin?), with the radio/cassette, the heat/vent arrangements, and two air-inlets in ascending order above. Servo controls make the heater quick and easy to operate, and ventilation is of a good order, helped by extra outlets let into the door mouldings. These also carry storage bins to complement the good-sized glove compartment.
After some intense driving through soggy Cornish countryside (the locals seemed to take particular glee in boasting of their rainfall) and long hours on the motorway there and back, I would rate the driving position and the seats highly: for once there is adequate support under the thigh even with the seat set back, and the hip-hugging effect of the velour-covered cushions allows the driver to relax. There is a rest for the left foot, and the short thick gearlever has a crisp movement.
Most welcome of all is the new steering system: previously the car had a rather stolid feel, with little sensation through the wheel and a directional vagueness which made motorways a trial. That is banished with the new variable ratio rack and pinion set-up giving 3.6 turns lock to lock, and providing two-way messages between the driver’s hands and the road surface. As part of the relentless advance in specification which the sportscar always heralds, four-wheel ventilated brake discs have now become common, so the RX7 turns to four-piston calipers up front. Braking stability is exemplary and the onset of locking tyres is easily felt and avoided, as I had cause to find out when a pile of planks fell off a trailer in front of me while thundering over Bodmin Moor.
Fifteen-inch alloy rims carrying Bridgestone RE7I tyres are standard; this is the tyre, known as Potenza in other markets, which has now been approved for fitment right through the Porsche range, including a 17in version which is original equipment for the staggering 959. It has a unidirectional arrow tread, and it really does seem to disperse water effectively, even through the pools of rain which fringed the Cornish roads.
A subdued whine is all that can be heard of the engine even at full stretch, so it is just as well that Mazda fits an audible rev warning; this high-pitched buzzer is easily triggered, particularly during overtaking when the driver’s attention is concentrated up ahead, because of the rotary’s eagerness to rev. It is just as happy surging through 6000 rpm as it is whirring steadily along village streets at a third of that, and the gear ratios are ideal for exploiting this. Just under 130 mph is available in fifth, and while third is often needed for brisk sprints, the light lever action and snappy flywheel response make for satisfying entertainment. However, like most entertainment, this must be paid for: fuel thirst has long been the rotary’s Achilles heel, and while each generation is better than before, the new RX7 barely covered a score of miles for every gallon of 2-star; 19.4 mpg overall, rising to about 20.8 on the motorway, is not impressive, even with the usual disclaimers about lead-footed testers.
What keeps the mpg figure down is the excellent balance of the whole car, and the temptation to exploit it. Nicely balanced, attentive to the steering wheel, and not easily upset by bumps, it changes direction instantly, and while the driver can feel the hub doing its switch-over trick, any slight steering correction needed to balance this is just absorbed into the normal wheel movements. Steering effort is not excessive; no need for power-assistance here, and the car’s blunt nose edges around holes and kerbs as quickly as the driver twitches the wheel.
This air of being all-of-a-piece extends to the light clutch, the solid brake pedal, and the short handbrake by the driver’s wrist. Creature comforts abound: windows, mirrors and sunroof are electric (the latter sliding back over the roof like that on the Honda CRX), the rear hatch pops open with a button, there are map-lights and kerb-lights under the doors, plus the sophisticated Clarion radio/cassette and electric aerial.
My only major grouse, setting aside the inevitably limited rear accommodation, is that the tipping seat-back, which springs forward after pulling a lever (watch your head), does not return to the same position — it has to be readjusted every time, a pointless annoyance. There is little noise intrusion (the suspension arms are subframe mounted with more clever bushes to absorb vibrations without upsetting stability), although the fat stiff tyres do thump in and out of holes, and a pleasant upright posture is possible with the various seat and wheel combinations.
Mazda has made this a very easy car to drive, but those who want to force the pace will not lose out because of that; it feels taut and precise, without becoming uncomfortable, and its sleek shape looks compact and purposeful. It boasts the delightful performance of Toyota’s little MR2 but with more space, in much more of a driver’s package than the same company’s Supra coupe. Head on with its intended Porsche opposition, it is a surprisingly good match for a 944, and surely a much more interesting car than the 924S, whose shape we have seen around for so long. A slightly deeper bootspace gives the RX7 a small practical edge over Stuttgart, but of course the German car’s superb engineering quality and reputation is something that even Mazda, with a strong reputation for reliability, will have an uphill struggle to wean customers away from, despite the increasing price gap: at £5,250, the Jap offering undercuts even the baby Porsche by nearly £3000.
There is little in the Mazda’s price bracket that falls into the same 22 coupe class: Nissan’s Silvia ZX (£12,195) is much less sophisticated, while the larger 300ZX is more ponderous. The Lotus Excel is only a little cheaper than the Porsche 924S; it has more poise, but inferior flexibility. Perhaps the Toyota Celica GT is closest in character, a pleasant and well-behaved hatchback of similar power at under £14,000. But, leaving aside those trading in old RX7s for new, it is the man about to replace his older 924 who is Mazda’s apparent target, and I suspect that should he become one of their “conquest” statistics, he will be a happy chap. GC