Tokyo--Just when you thought it was safe to assume that pistons running up and down in cylinders were a vital part of all great driving cars on the road today, Mazda begs to disagree. Remember rotary power? It’s back, courtesy of the RX-Evolv, an all-new rotary concept car that debuted at the Tokyo Motor Show.

We knew beforehand that Mazda was planning a rotary “surprise” for the show. Even so, when it was shown in public for the first time, the RX-Evolv still caused eyes to widen, because it’s a genuine mold breaker. It’s not what we were expecting.

True, the brand-new 276-bhp twin-rotor engine buried deep in the car’s nose is fascinating in itself, not least because enthusiasts in the United States could be forgiven for thinking that the rotary engine (along with the RX-7) had already died and gone to automotive heaven. However, it turns out that the resurrection of the turbine-smooth rotary is only one part of this remarkable new Mazda’s bill of fare.

The shape of the car and, in particular, the four-seat packaging complete with rear-hinged rear doors, is also new—wild, even by Mazda standards, harking back to the first Cosmo and RX-7, both of which went decidedly against the grain. Mazda conceived the RX-Evolv as a sports car for four people, which is very fresh thinking.

The RX-Evolv is neither a sedan nor a coupe. Nor is it an RX-7 (in the traditional sense) or a converted Miata. Instead, the RX-Evolv boldly goes its own way. This is the car that factions inside Mazda wanted to call the RX-8, and it might just end up with that badge should it get the production green light.

At the start, the rationale behind the RX-Evolv was to consider the driver who perhaps owns a Miata, gets married, and has children. Then what? Obviously he or she needs more than two seats. However, there aren’t too many cars out there that offer a true, rear-wheel-drive sports car feel and four proper seats. In fact, there aren’t any, unless you count sport sedans like the BMW M5 and the Mercedes-Benz C43 AMG.

So the RX-Evolv was conceived to fill the niche of the most sports-car-like, four-door car in the world. Oddly enough, it starts out being about the same size as the last RX-7 to do duty in the United States—168.7 inches long and 69.3 inches wide. But it’s nearly five inches taller than the RX-7, and the 107.1-inch wheelbase is almost twelve inches longer than the RX-7’s. Thus, Mazda’s concept deals handily with one of the biggest foibles of the latest (in Japan) and last RX-7: lack of cabin space.

Lanky six-footers can sit in the back of the RX-Evolv even while equally lanky six-footers sit in the front. This is pretty radical stuff by sports car standards. The same goes for Mazda’s decision to use pillarless rear-hinged doors—or as they are known around Hiroshima headquarters, freestyle doors. Yes, they look strange, but they’re seen as being absolutely true to the underlying concept of the car: that it should cater to the rear passengers just as much as those in the front. By going freestyle, the simple act of climbing into and out of the car becomes much easier. Mazda claims that its use of hydroforming, in which the car’s steel body structure is formed under hydraulic pressure, makes the RX-Evolv’s pillarless body just as rigid as a conventional sedan’s, albeit with a slight weight penalty. In the meantime, all the legal and safety ramifications will still have to be checked for production. “But we will try to keep that part of the design if we possibly can,” says Martin Leach, who was until recently Mazda’s R&D chief.

The cabin of the RX-Evolv, conceived by Wu-Huang Chin of Mazda’s West Coast design studio, is a masterpiece of color coordination, design, ergonomics, and quality. Mazda’s previous rotary show car, the RX-01 from the ’95 Tokyo show, wasn’t put together nearly as well. The brown and silver lightweight sport seats with see-through wire mesh centers look great and provide real support. Underlining (again) that this is a whole new type of sports car and a different market, both sets of seats slide on runners. The passenger’s-side rear seat even comes with its very own built-in, fold-down child’s seat.

Domesticity only goes so far, however, and for the driver, the RX-Evolv has several surprises in store. Greeting you is a speedometer that reads up to 280 kph (174 mph) and a tachometer that tails off at 11,000 rpm. This is a good start. Down below, there’s a red start button and a green one bearing the defiant message “kill.” Another red one-touch button activates the hand brake. On the center console, Mazda has come up with a tiny silver transmission joystick. You can either let the six-speed clutchless transmission shift gears for you, or you can buzz up and down using steering-wheel-mounted paddles, Formula 1–style. Mazda calls them wing shifts. Right to shift up, left to shift down.

Fans of video arcades will really appreciate the next bit. Although the RX-Evolv comes with massive vented disc brakes (six-piston calipers up front, four-piston for the rears), Leach and his team have devised one very special tweak, the Active Cornering Brake system (ACB), which allows the driver to use small levers on the steering wheel to call on additional braking force on each rear wheel as and when he wants it—for example, to kill understeer in a bend and pull the nose into the apex. Press on the left lever to activate the left rear brake, the right lever to work the right.

There’s more techno-trickery. An ID Access card that opens and locks the doors also starts the engine and engages the car’s security system. This smart electronic card also stores information on the driver’s level of skill: For an inexperienced pilot, the engine power and torque are automatically lowered to 237 bhp and 152 pound-feet.

In full cry, however, Mazda’s new free-revving, twin-rotor engine (called Renesis, for RE—rotary engine’s—Genesis) produces its 276 bhp at a ballistic 9000 rpm; the 166 pound-feet of torque peaks at 8000 rpm. “[This is] the highest power density ever achieved by a normally aspirated engine for a roadgoing automobile,” notes Leach proudly. Mazda insiders also say the engine sounds fantastic. The new rotary builds on the small and light qualities of the MSP-RE (Multi Side Port) rotary from the RX-01 show car. In a raft of improvements, the intake and exhaust port areas have been redesigned and enlarged, thus greatly im-proving flow through the engine. A new three-stage induction system optimizes chamber filling. There are also thinner lightweight rotors, a higher 10,000-rpm rev limit, and an increased compression ratio. There’s no change in the 654-cc displacement of each chamber, however. As for economy and emissions, there’s still some work to do, but Renesis no doubt will be much greener than the 13B-REW unit in the RX-7 that’s still on sale as a 276-bhp cult hero in Japan.

With the new engine mounted in a front-midship location low down behind the front axle line, and with heavy items like the fuel tank also carefully positioned within the wheelbase, Mazda was able to achieve a perfect 50/50 weight distribution. The engine is accessed via a clever, forward-tipping double-clamshell hood. Anyone expecting to see a macho array of Viper or Corvette-like pipes and cam covers when looking down at this new super rotary will be in for a disappointment.

The chassis has pedigree. The RX-Evolv rides on four-wheel double wishbones with aluminum arms and knuckles. Mazda-designed five-spoke alloy wheels wear 225/40ZR-20 front and 245/35ZR-20 rear tires that fill out those wheel arches and give this low-slung rotary speedster a really muscular stance. With finely calibrated steering and a low polar moment of inertia, the RX-Evolv should be truly something through turns. Mazda says the car has “never-before-experienced chassis dynamics.” Okay, then.

The sensual shape was overseen by Yoichi Sato, head of Mazda’s Hiroshima Advance Design Studio. Seen from the front, the narrow horizontal air intake hides a pair of equally narrow high-intensity-discharge headlights. The doors are deep and the side windows narrow. The windshield is raked right back. There are no body overhangs to speak of, but check out the subtle RX-7 styling cues in the double-bubble roof (current Japan-market RX-7) and thick C-pillars with sloping roofline (reminiscent of the first model from 1979–85). The taillights mounted on the rounded lid of the 8.8-cubic-foot-capacity trunk are distant cousins of those on the Miata. Talk about the design, the packaging, the colors, and the coordination, and Sato looks happy. “Everything works,” he says. Reintroducing the rotary, always a matter of intense pride inside Mazda in Japan, caps it all off. But now comes the job of reminding the world at large what it can do.

From here on in, much depends on the reception the RX-Evolv gets, not least in the United States. Price is obviously a factor. “We’ve been told the car must be affordable, but we haven’t yet decided what affordable is,” says Leach with a wry smile. “But we’ve also been told that if we bring it into Japan for less than Ą3.5 million (about $33,000 at current rates), we’ve got a winner.” Another target is a curb weight of 2626 pounds, and to get there, Leach says he’s set up a “gram force” to cut weight. Another goal for the RX-Evolv is a sub-five-second 0-to-60-mph time, so the car promises to be breathtakingly quick.

There’s no doubt that everyone at Mazda wants to inject some more excitement into the brand, and the RX-Evolv seems to be a great place to start. According to Leach, from show car to sign-off could take as little as two years. Let’s hope so.