The Volvo C30 is based on the same platform as the S40 and V50. All share the same 103.9-inch wheelbase, but the C30 is 8.5 inches shorter, all behind the rear wheels. Up front, the C30 is similar to its siblings, with the characteristic Volvo upright grille and sharply v-shaped hood.

Volvo designed the C30 with two doors and the design is striking, particularly from the side. The roofline starts out high and slopes gradually down, pinching the rear windows. Those windows are drawn in, leaving room for another Volvo characteristic, pronounced shoulders. Sporty characteristics include short front and rear overhangs, an integrated body kit, and big wheels on wide tires. The ground-effects-type body kit outlines the bottom of the car from front to rear and includes wheel flares at all four corners. On the 1.0 version, the body kit is rendered in a textured contrasting flat black plastic. On 2.0 models it is painted a contrasting gloss color, and Volvo offers several colors so customers can personalize their cars.

The story isn't the C30's front or sides, though. It's at the rear. Volvo is putting more emphasis on the rear aspect of the C30, choosing to show that angle in promotional materials. The most prominent feature is the dark-tinted rear glass, an attractive frameless trapezoidal shape that recalls the rear of the 1971-73 Volvo P1800 ES wagon. The glass dips down low and is flanked by unique taillights that rise up to the roof and jut out at the bottom to match the shape of the car's shoulders. The look is different from anything out there and is strong enough to give the car a distinct character.

All C30s have alloy wheels, with 17-inch wheels standard on 1.0 models and 18-inch wheels standard on 2.0s. Sixteen-inch wheels and tires are available as well, for drivers who value ride quality. The look is more attractive and more menacing with the 18s. Only five exterior colors are offered as standard options, but the Custom Order Options up the total to 16.

Volvo views its main competitors as the Audi A3, Mini Cooper S, and Volkswagen GTI. The C30 has a longer wheelbase than all three. Like the A3 and GTI, it's about two feet longer than the Mini. From the rear, it has more character than any of those competitors, including the Mini. From the front, it would be easy to mistake the C30 for its S40 and V50 brothers.