Design consideration #2. - Let the comments fly...
Put turbos at the back of the engine compartment by the tranny; there's more volume there. Put the radiator, fuel cell, and intercooler in front of the engine at the widest point. Cockpit between the front wheels and engine compartment; this, again, it is to keep the widest things in the middle like JHN says. Bump the cross section around the engine to include decent manifolds. Lots of power and reliability is lost in current designs from inadequate manifolds (especially in the 400 mph club. I apologize for this, we all need to look at other motorsports to see what optimized turbo intake and exhaust manifolds look like when people have spent millions of dollars on a few percent gain. Specifically look at Indy car.)
The "frontal area" does NOT matter. #1 is separation (no blunt tails), #2 is wetted area (smaller is better, look at Wheeler), #3 is laminar run. I hope I have time this year to write an article on this for the LSR community that explains these issues in terms that will help everyone design better cars. Everyone who posts here is more than intelligent enough and experienced enough to understand the truth about aero vs. the myths. But it's not intuitive, and there's a lot of bad information out there.
Yes, neck down the sides of the body just in front of the wheel fairings, then go straighter aft over the diff's, then taper to a point. Yes, a point. Any, and I mean ANY blunt tail will create more drag than the entire rest of the car. Tandem (side-by-side) fronts will be higher drag and harder to fair than in-line; solving the steering will be the other way around. I'm working on that.
Last, with all due respect to the records and speeds established by the Costella and Costella-type designs, drag build up calculations show all those flat bottoms and blunt tails are in fully separated flow. To go faster, we need to get back to what makes downforce with the least drag, not the most: i.e. wings, not ground effects. Good wings can produce 5 to 30X the downforce-to-drag ratios of any ground effects. They are less sensitive to ride height and do not cause lifting when the car gets out of shape. Good wings have a 5 to 30:1 L/D; ground effects are lucky to hit 1:1.
To any who wish to use ground effects, I urge you to read "Race Car Aerodynamics" Joseph Katz ISBN 0-8376-0142-8. Air going
under the car is what creates downforce, not the other way around.