The overriding exterior design theme was "Athletic Tension". This approach was used to convey a feeling of expectation or pent-up energy ready to be released, much like an athlete waiting for the starter's gun. The design team focused on weight reduction, aerodynamics and modern proportioning, while shaping the car to evoke three main attributes; dynamic form, tension and stability.

The most distinctive feature of the RX-8's design is its dynamic body. The dynamic form is evident in the powerful continuity of surfaces is expressed in 3-dimensional relief, starting at the front air intake and running aft, along the body sides to the boot lid.

The effect of vitality and motion is achieved through the sculpted surfaces of the body rather than 2-dimensional character lines. From every angle, the RX-8 gives the impression of a high-performance car - aggressive, yet stylish and original.

Tension is expressed by trimming body mass to produce an extremely taut form. With the elegance of an athlete, RX-8 also features mechanical overtones in the headlamp and rear combination lamp design. The rotor-shaped power bulge in the hood and subtle shaping in the roof work in contrast to convey an overall feeling of tension on the body surface.

The entire body is sleek and trim, with smooth, taut lines that suggest the alert readiness of an athlete in peak condition. In particular, the front fenders and door panels have a pronounced 3-dimensional form unseen in other cars, giving a lean and powerfully muscular impression.