Mid-engine, 2 seat obviously. I kinda like the V6 sound, but I also like the sound of a high rev'ing 4 cylinder (such as the S2000) better. Acceleration should be on par with a S2000*. Weight? Hopefully they could keep it under 3000. Roadster with an optional removable hard top. Transmission options: manual and some kind of semi-automatic (sequential manual or dual-clutch). 18" wheels with appropriate sized ABS brakes. Traction control and stability control that can be disabled. A suspension that's adjustable from the cockpit, with settings suitable for daily driving, "sport" driving (on the street), and track days/autocross. Enough storage for 2 people for a weekend. And, of course, styling that obviously says, "Fiero".
* I would actually NOT want it be extremely fast. Cars with extremely high performance limits are boring at anything close to legal speeds. I would want to be able to enjoy it without having to drive it at "go directly to jail" speeds. You really can't enjoy a Ferrari, Porsche or Corvette at their limits anywhere but a track. Plus, if it's TOO fast, the Corvette team would try to kill it.
Oh yeah... $25000.
Yeah, right. It would probably be more like 40K.
Re: pop-up headlights.... They're no longer legal. Speaking of headlights... I would NOT want headlights that were $3000 each for replacements (like some LED systems now).