The RX-01 is Mazda's next vision of what a true sports car should be. Despite being 2.2 inches shorter than an RX-7, it offers 2+2 seating, a larger trunk, and 2.8 inches more front crush space, thanks in large part to its compact new rotary engine design. Based on the venerable 13B twin-rotor, the new engine moves the exhaust ports from the rotor housing to the side housing. The side-exhaust ports can be timed to close earlier than the peripheral port, which allows the intake ports to be enlarged for better air flow, and their manifolding is more compact. A dry-sump lubrication system further reduces the package size of this little 227-horse naturally aspirated hummer. As a result, the engine sits 8 inches farther back, and 2.2 inches lower in the car than the RX-7 engine.
That kind of packaging is a stylist's dream. The RX-01's hood slopes down almost as sharply as that of an Acura NSX, and it incorporates an air foil which provides downforce. Magnesium wheels are bolted to aluminum rotors with aluminum calipers and shock absorber housings, to keep unsprung weight to a minimum. A central-discharge lamp (CDL) lighting system feeds the headlamps via fiber optics. The total weight of this sleek little sportster is estimated at 2425 pounds, or 400 pounds lighter than the already feathery RX-7. A naturally-aspirated rotary will be easier to clean up to LEV standards than the turbo is, but Mazda cash is short, so don't hold your breath for this one.
The RX-01 looks extraordinary and sounds great. As for its looks, the lower body with its integrated front wing is fabulous, while the double-bubble top may not be everyone's cup of tea, green or black. But as a concept car shown at the Tokyo show, some controversies over its styling are intentionally invited. And a key development person confides that the top can be cut off to turn it into a convertible. That's more like it.
The sounds come from the latest development of the familiar type-13B twin-rotor Wankel sans turbo. It inhales and exhales through the side ports. The engine growls at low rpm, smoothly changing to a nice baritone in midrange and into a fantastic tenor at high speeds, more than 8500 rpm, at which it pumps out 220 bhp. Low- and mid-speed torque is quite good, culminating at 159 lb.-ft. at 6000 rpm. The engine's dry-sump lubrication system allows its location to be pushed back 8.0 in. and lowered 2.2 in., so that it sits well aft of the front axle. The engine is mated to a 5-speed manual transmission with typically short throws that have marked Mazda sports-car gearboxes. Locating the power unit, battery and fuel tank within the wheelbase means extremely low polar moment of inertia, some 30 percent lower than the already agile RX-7, according to Mazda.
The chassis is a mixture of RX-7 and Miata components, with unequal-length A-arms all around and vented disc brakes. The car is quite compact (159.6 in. long, 68.1 in. wide and 49.0 in. tall), accommodates 2+ (a very small) 2 and has a usable trunk that takes two sets of golf clubs. A new CDL (central-discharge lighting) system illuminates the slit-like headlamps, which are not quite at Japan's legal height (nor America's).
The RX-01 is a thoroughly feasible sports car, developed by a team of young engineers from the Hiroshima company's product engineering division. I hope the powers that be, at Hiroshima and Dearborn, will approve the project.--Jack Yamaguchi