Under the vented and liveried bonnet resides a version of Subaru's 2.0-litre turbocharged four-cylinder boxer engine, which for the VT15x has been tuned to deliver around 432kW (580hp).
Power is sent to all four wheels via a six-speed Sadev sequential transmission. Subaru claims that the VT15x is capable of racing from 0-96km/h (0-60mph) in two seconds.
The VT15x is built by Vermont SportsCar, and is said to be a "revolution, not just an evolution" over the previous VT14x vehicle.
According to Subaru, both STI and Vermont SportsCar have worked hard to ensure that the new car has improved an weight balance and centre of gravity, as well as bucketloads of extra power.
Other changes include work on the car's suspension geometry and aerodynamic properties.
The VT15x is scheduled to make its debut at the New York auto show, which begins tomorrow. The car will then compete in the Red Bull Global Rallycross and X Games Rallycross.
Last year, the VT14x car was able to gain a number of podium places throughout the Red Bull and X Games seasons. This year, Subaru and its partners say that "our only goal is winning".