The Kestrel 4000 is currently being tested. Extensive aero drag tests were completed in a wind tunnel to give a shape that’s supposed to be 20% more aero than Cervelo’s P3 benchmark. Kestrel initially tried putting the brake caliper behind the fork and inside of it. However, this turned out to be less aerodynamic than in the traditional position. Before you ask, yes, it’s UCI approved!
When I originally got my 1st bicycle, a Columbus steel Pinarello with Shimano 105, carbon fiber bikes by Kestrel were just beginning to become popular. I’ve always wanted one.