Jet pilots train to withstand 9+ g's during flight. Do you mean to tell me a 300 mph car would pull more g's than an F-16 at or over the sound barrier?
They wistand G's in such a way that the blood pushes down towards their feet, which a G-suit can compensate for.
Turning a racecar is an entirely different direction of blood rush.
X1 was created to answer Kazunori Yamauchi question on "If you built the fastest racing car on land, one that throws aside all rules and regulations, what would that car look like, how would it perform, and how would it feel to drive?"
And voila, a fictional racing car was born.
I'm sure if they really want to build one, they will be able to do it. Just that they haven't, and see no point in building one cause it will just go against the racing regulation and is a total waste of money and effort.
My 2 cents worth.
Like a Zonda R?