One major change in design between the RX-8 and the RX-7 is the addition of a pair of rear-hinged ('suicide') half-doors (similar to the 3rd door in the Saturn coupe), which allow easier access to the two back seats. The RX-8 has no center pillars seperating the front and rear doors. The front doors are hinged at the front, and aluminum back doors are hinged at the rear. A safety lock mechanism allows the back doors to open only if the front doors are open. Weight distribution in the RX-8 is a balanced 50/50 in the front and rear. Mazda’s new rotary engine is smaller and lighter than prior rotaries, yet it yields more power. New to its design are a side-intake and side-exhaust. To cut down on cost, the RX-8 does not come with a turbocharger or supercharger, like the RX-7's. The engine produces 210 horsepower in the automatic transmission form, and 250 horsepower in the manual transmission form. Mazda aggressively trimmed mass from the RX-8 concept by using aluminum and plastic for body panels and installing a carbon composite driveshaft. The dimensions of the RX-8 are virtually identical to those of the Porsche 911 Carrera.
According to Mazda, the RX-8 was originally developed to potentially use either gasoline or hydrogen as fuel (CanadianDriver Communications, Inc., 2004).