I don’t think think the underground racing galllardo would ever pass the Veyron.
Note the two dyno plots directly from UR and Bugatti.
Veyron:
UR TT Gallardo:
They Veyron has 100 ft/lb more across the board. Those ft/lbs arrive over 2500 RPM sooner, and the Veyron has more gears. The Veyron looks to be putting down about 973 hp at the wheels.
The Gallardo may make 1073 hp at the wheels, but this in only a mathematical artifact of it’s high Redline. The Veyron has much more area under the torque curve, and it gets that torque sooner.
The Veyron weighs a staggering 4162lb
The stock Gallardo 3459. we should add 100lb for turbos and intercoolers perhaps. Basically the Veyron weighs 600lb more than the Gallardo. Now that is a lot.
Power advantage: Veyron
Weight advantage: Gallardo
For reference the Veyron makes 922 ft/lb for 3300 rpm. an area of 3.04m units.
The UR Gallardo: about 790 ft/lb average from 4750-8000rpm. Thats 3250x790 or 2.56m units.
That’s about 18.56% more area under the curve for the Veyron.
But it weighs 20.32% more than the Gallardo. 16.94% if you add 100lbs of turbo kit the stock Gallardo.
As you can see this is a close race on paper. However I think the fast power delivery of the Veyron will allow it to eek out an early lead, and maintain it by the slimmest of margins. On the street this race would be all driver.