The car has a full flat bottom which is probably the most elaborate part of the whole car. The flat bottom contributes greatly to the effectiveness of the rear diffuser and front splitter. There are no places for air to leak around the car to lower a splitter stagnation generated pressure differential. The full flat bottom sees to that. The belly pan is constructed of honeycomb reinforced carbon as is the splitter. The splitter although sturdy, ended up not being strong enough for the high speeds of Buttonwillow. You can see how it is battered and splintered. It was just put back on for photo reasons.
Look at the nice uninterrupted flow path to the rear diffuser. It is hard to get a rear diffuser to work really well with partial belly pans. We feel that the flat bottom is one of the car's secrets for speed.
The splitter turns the cosmetic air dam into a highly functional piece. How well did it work? When it broke off Dai reported that the car immediately developed severe understeer and his lap times dropped by 3 seconds a lap even with new tires. We think that the car's front aero could be made 30% or more effective with no drag penalty by blocking off and reducing some of the superfluous front vents in the nose and making air ducting to the front heat exchangers.
With no air flow path to the bottom of the car available, air pressure can build up inside the engine compartment. The hood is generously vented and the rear area left open to alleviate this and direct air flow over the top of the car, reducing drag and helping the aero bits work better. The base of the windshield is usually an area of high pressure but this car has a higher engine compartment pressure than most due the the flat bottom and the windshield has a lot of rake.
The Spoon Civic's rolling gear is Rays Gram Lite 57DR's in 18X10.5 with a 22mm offset. The tires are Advan A005 medium compound road racing slicks.
You can see the blister flairs done for tire clearance. This is pretty simple, no aggressive wide body done here.