Ferrari has unveiled its latest one-off supercar, the HC25, which is based on the F8 Spider.The nonhybrid twin-turbo 3.9-liter V-8 produces 710 horsepower, allowing the HC25 to blast to 62 mph in a claimed 2.9 seconds.The HC25 features slim headlights and a black band that surrounds the engine cover, creating two distinct sections of the car, interrupted only by a bar milled from solid aluminum.