The original show car was an 'automotive sculpture' by Jaguar. We were then given the job of producing a car which looked the same and performed to the anticipated level (220mph!) when people wanted to buy the thing!
Yes, budget constraints there were, but solid engineering reasons for the change of engine. The V12 was too big, too heavy and would not produce enough power within the emission regs to push the car to the right speed.
Then there was the question of tyres. Nobody produced a tyre capable of supporting a car of that mass plus downforce at that speed.
Given the amount of platform and technology sharing that now goes on, it still amazes me that a car and engine were designed, developed and produced when the numbers were limited to 350.
As I think you will know, it costs Buggatti £5m to produce each car when development costs are factored in.
I now think that the idea of a car which tries to do both racecar and roadcar is flawed. The two are so completley different you need two different cars.
It won't stop people trying though!