It's the stock white, believe it or not.
The trick is the place in which it is taken, the yellow lit, very long tunnel at Route X, the DLC oval.
The effect is best near the entrance and exit of the tunnel, as the middle of it is rather dark, as you can see here:
Unfortunately, all of this limits the possibilities, but you could always experiment with different car colors, angles and editing.
Here's some more examples of what can be achieved, scaled down as they're off-topic, really: