The 'trompe le vent',wind deceiver,Ricotti car is reported at a top speed of 86 mph,vs 68 mph for the car it was based upon.That's a 26.4% velocity increase,with no added horsepower.According to Hucho's metric,this would suggest a 79% drag reduction,in spite of it's overall frontal area increase.
One source reported Cd 0.54 for the Ricotti