This article also appears in
Subscribe now »

Mazda RX-Vision concept.

Sports cars take center stage in Tokyo

Once upon a time, the Tokyo Motor Show was considered one of its biggest. However, not anymore, in terms of its acreage, numbers of exhibit brands, and visitors; it is now dwarfed by such Asian aspirers as Shanghai, Beijing, and Seoul. The show’s allure had hugely diminished when most of the foreign continents lost their Big Sight venue spots for a couple of shows after the Great Lehman Bros crisis.

The show was back in town this year, with the Japanese car, commercial vehicle, motorcycle manufacturers, suppliers, and specialists returning to the arena with delightful and energetic vengeance. The country still ranks third in the world for new automobile sales (5.56 million in 2014), and the imports have been doing well with a relatively small share (5.2% in 2014) but lucrative business. The importers were back as well, notably with two extraordinary world premieres, one automated concept by Mercedes-Benz and the other an ultra-high-performance car courtesy of BMW. Prominently absent were General Motors, Ford, and the envy of the Japanese Four in the premium two-wheel segment, Harley-Davidson.

The show’s prominent themes were sports cars (the subject of this article), automated driving, electrification, and boxes-on-wheel designs, sometime in combination in single vehicles.

The show opened with Mazda’s unveiling of the RX-Vision concept and the revival of its Wankel rotary engine, now officially named Skyactiv-R. The exciting two-seat coupe was shaped under the direction of Ikuo Maeda, the Hiroshima company’s Design Director extraordinaire. It is a mockup with interior but fixed doors, with few technical details released, except dimensions of 4389-mm (172.8-in) length on a 2700-mm (106.3-in) wheelbase, 1925-mm (75.8-in) width, and 1160-mm (45.7-in) height, riding on 1454/40R20 front and 285/35R20 tires.

Few details were released on the Skyactiv-R engine that was not under the hood, which was so long that speculation was that the motor could have four or even six rotors. It is actually a two-rotor unit, its roots going back to the 16X unit circa 2007 in a curious Laurens van den Acker (now Renault Design VP) era sports car concept. Later, the designation briefly surfaced at a technical workshop but on the screen only.

Mazda’s rotary research and development continued after the end of RX-8 production, with some 40 engineers and technicians, according to Hiroharu Akagi, then Deputy Director of Powertrain Development for the rotary and now responsible for Mazda’s advanced powertrain research and planning. The 16X project even had a proper alphabetical progression that was not revealed. The numeral 16 indicated the engine’s single chamber volume of about 800-cm³ (times two rotors) vs. the last production 13B’s 654-cm³. No other internal dimensions have been released to date. The Skyactiv-R may be described in reciprocating piston parlance as “small-bore, long stroke.”

The rotary engine's three dimensions determine displacement: e for eccentricity, the amount of offset between the eccentric shaft center and the rotor center line; R for radius of generating radius, the distance between the rotor center line and the rotor apex; and b for width of the trochoid rotor chamber. Historically, b has been the variable, obtaining different single chamber capacities. The last production 13B twin-rotor and the 1999 Le Mans 24-hour winning R26B shared the same internal dimensions of e = 15 mm (0.59 in), R = 105 mm (4.1 in), and b = 80 mm (3.1 in). Mazda’s first production engine that powered the 1968 R100 coupe had a single chamber capacity of 491 cm³, with a 50-mm (2.0-in) b.

There was one oddball production engine called “13A,” circa 1967, which had unique dimensions of e = 17.5 mm (0.69 in), R = 120 mm (4.7 in), and b = 60 mm (2.4 in) for a single chamber volume of 655 cm³. The engine was placed in the front overhang, and drove the front wheels; therefore, its short length was important.

Akagi said that the rotary team had arrived at an optimized set of internal dimensions, smaller axially (bore) and longer radially (stroke), while closely adhering to the proven epitrochoidal constant. Total length of the apex seals, three sets for each rotor, would be about the same as the production 13B, and a higher compression ratio could be employed, improving thermal efficiency.

On the RX-Vision sports car concept, Design Director Ikuo Maeda confided: "The project is ongoing, whatever powertrain it may employ," an encouraging but enigmatic observation.

As with Nissan’s mega sports car vision, the 2020 Vision Gran Turismo, Sony's PlayStation has inspired and digitally helped many a product planner, designer, or race driver in the person’s chosen path. Several automobile manufacturers are known to have joined forces and resources with Kaz Yamauchi and his Polyphony Digital game in creating racecars that compete on digital tracks. The Nissan concept is the latest example, passionately and professionally created at the Nissan design studio. It is no surprise that the mockup, sans interior, has design cues of the current GT-R, and like the supercar, it is a 2+2 coupe powered by a Le Mans LMP1-type twin-turbo V6 and three-electric motor hybrid system not unlike that of the new Acura NSX. The body intends to incorporate a number of innovative aerodynamic features.

Honda is another company that has collaborated with Polyphony Digital, but not this time. It's latest concept, called Project 2&4, represents a synergy between two major units of Honda, the automobile and motorcycle design groups, and more significantly represented by two Americans from Torrance, CA and Asaka, Japan. The sporting machine's hind end bears the automotive “H” and motorcycle “Wing” emblems. The 3040 mm (119.7 in) long and 1820 mm (71.7 in) wide mid-engine concept is built on a welded aluminum backbone chassis with racing type suspension all around. In its normal configuration, it seats one person, the driver in a “floating seat.” Remove the panel on the other side, hang a similar seat, and voila!—a daring passenger may be accommodated as on a bike. The 2&4’s motive power is provided by the Moto GP (Formula 1 on two wheels) 215-PS (158 kW) at 13000 rpm, 999-cm³ V4 that drives the rear wheels via six-speed dual-clutch transmission. The vehicle weighs all of 405 kg (893 lb).

Yamaha pulled a show surprise. The Hamamatsu-based company has not sold a single car, yet it has played important roles in the design and development of sports cars, as early as 1960s all the way to Toyota’s LF-A supercar. Yamaha was commissioned many years ago to develop a sports coupe by Nissan. It was equipped with a DOHC inline six and all independent suspension. It ran superbly, according to Fumio Ito, Yamaha’s ace Grand Prix motorcycle rider, who remarked that an MG MGA Twin Cam was no comparison. A row between the two companies’ presidents put the project on the shelf. Afterward, Toyota approached Yamaha to design and develop a sports coupe that became the 1967 Toyota 2000GT. Nissan then proceeded with its own project, the Datsun 240Z.

In the nineties, Yamaha supplied Formula 1 engines of its own design and development to a few constructors, and planned to build a supercar powered by the type OX11 DOHC 3.5-L V12. A lone example, essentially a tandem-seating canopied F1/F3000 designed by Takuya Yura, was unveiled in London in May 1992. The project was aborted in an ensuing economic crunch.

Yamaha showed a city car concept called MOTIV at the 2013 Tokyo Motor Show, with a unique composite tubular steel and carbon-fiber construction conceived by Gordon Murray of Formula 1 fame. Yamaha applied that technology to this year's Tokyo Motor Show surprise, the Sports Ride Concept, a mid-transverse engine, two-seat sports coupe. Its exterior was designed by the young Korean designer Jeung Hyun Choul under the direction of the hugely talented and flamboyant (part-time pop musician) Dezi Akihiro, formerly with Lexus and Toyota. Nagaya is proud of Yamaha’s motorcycle heritage, and the Sports Ride carries many design cues, a V-nose, and a plastic knee pad in the driver area. The car is compact, measuring 3900 mm (153.5 in) long, 1720 mm (67.7 in) wide and 1170 mm (46.1 mm) tall, and it weighs only 750 kg (1653 lb). No mechanical details were announced, but not to worry, the powertrain department at Yamaha has produced a large variety of automobile performance engines. Nagaya declared that Yamaha was very serious about getting this car to the marketplace.

Toyota presented its interpretation of a bike-like vehicle called Kikai, a translation of “machine.” Lots of mechanical pieces are exposed except a central cage that accommodates three people, the central driver and rear/side passengers a la McLaren's F1. Its powertrain is a Prius C-type 1.5-L engine/hybrid system mounted amidships. The steering-column-mounted selector lever and four circular gauges are nostalgic throwback features. Doubtful for the show room because of its myriads of protrusions, unless it is classified as a bike (unlikely), it is a charming concept for the solid corporate citizen.

Toyota's small 2+2 coupe concept called S-FR, presumably short for Sports, Front-engine, Rear-wheel-drive, could be a perfect addition to the Scion range of youth-oriented cars. The popular formula for a sports runabout has outer dimensions that conform to Japan’s small car category at 1695-mm (66.7-in) width, just under the 1.7-meter rule. It features independent suspension, not visible in the mockup, again presumably by McPherson struts all around. The classification’s engine size is less than 2.0 L, which should be comfortable enough in this age of downsizing, likely a new 1.5-L inline four. According to an attending engineer, Toyota is aiming at a curb weight of 1000 kg (2200 lb) or less. The S-FR’s rounded, no-crease bodywork and cartoony countenance are intentional, the said engineer confided.

It had been a long time since the last non-Japanese world premier graced the Tokyo stage (e.g. Audi’s Avus and Daimler-Benz’s Maybach concept, the latter a heart-child of the company’s Yokohama design studio). This year Munich and Stuttgart brought one each in the form of the sporty BMW M4 GTS and van-like Mercedes-Benz Vision Tokyo.

BMW’s M4 GTS coupe is a serious performance machine, its sight squarely set on the racetrack, proclaimed BMW M GmbH. It cites a lap time of 7:28 minutes around the Nurburgring’s Nordschleife. Or one could readily do a 0-100-km/h stoplight grand prix in 3.8 s, one’s driving license permitting. Unique in the M4 GTS is an innovative water injection that hikes its DOHC Twin-power turbo 3.0-L inline six engine’s maximum output by 16% to 368 kW (493 hp) and torque by 10% to 600 N·m (443 lb·ft) compared to the stock M4's. Water is injected into the cylinders above 3000 rpm. A 10-L (2.6-gal) tank is to be filled with a mixture of distilled water and anti-freeze at about every fifth fill-up of gasoline, according to the attending engineer. When the engine is turned off, water is returned to the tank, so no fear of freezing. There had been some precedence with water injection including in the Saab 99 Turbo and 1962 Oldsmobile F85 with Fluid-Injection Jetfire engine. BMW is offering 700 M4 GTS models.

Continue reading »