This is what they have in the press release:
The build features an electric motor consisting of LEGO Technic Function batteries and an electric car battery, allowing it to travel further than any other LEGO model before it.
The LEGO Technic engine consists of 8 motor packs, each consisting of 96 LEGO Power function motors, which means the car features a total of 768 LEGO motors. The 8 motor packs imitate the V8 seen in the original McLaren P1™.
I reached out for clarification but didn't succeed yet, they practically repeated the same thing. I have no idea what "LEGO Technic Function batteries" are supposed to be, but I think besides the 768 Technic motors they used a proper electric motor, and also an EV battery, so the heavy lifting should be done by real automotive parts. I highly doubt the top speed of 40 mph was achieved by LEGO motors only, the Chiron could only do 20 km/h and that had 2304 LEGO motors.