The answer to your question can be found in all the low drag vehicles with open wheel wells. You won't find flares on the bodywork (not counting spats to direct flow around the tread face of the exposed tire).
I expect someone may chime in here with the example of the newest Prius bumper bodywork ahead of the front wheel arches, which is claimed to help. I'm on the fence on that one until I can learn more about it. But it's not really a flare - definitely
doesn't increase frontal area.
The flares on the Top Gear Rabbit may get air away from the tread face of a wider tire, but I bet you a donut the flow behind the aft edge of the arch is a mess.
