[ShadeTreeMech]

I think your answer to the question of sportscars being less aerodynamic can be found in the article quoted above.

"For best cornering and racing performance, as required in Formula One cars, downforce and stability are crucial and these cars must attempt to maximize downforce and maintain stability while attempting to minimize the overall Cd value"

quoted from wikipedia

A camry isn't designed to corner at high speeds as well as a Corvette. For example, my Maxima corrners very well, but will understeer if pushed too hard. If I were to add a front spoiler, air pressure would press the tires into the pavement allowing me to go a bit faster without understeering. BUT it would make the maxima less aerodynamic.

I was reading a good and very well detailed article on here mentioning the mods that had been made to a 1st gen Prius in Aussie. They talked about how adding a partial belly pan under the front bumper added a bit of instability; ie the steering got light at speed. the reason is the angle the air hit their pan caused lift and taking weight off the front tires. They added some of those aerodynamic wedges found on the back of an Evo to the underside and that stabilized it, possibly from disrupting the air flow.

reading that article helped me to realize simply adding a pan would be a bad idea without first adding an airdam under the front bumper to either induce a bit of downforce or make it aerodynamically neutral. I do too much steering in the Ozark mountains to afford to ignore the need to go around a corner at speed.