Monsoon-level rain is fired non-stop at the Chiron for 30 minutes to check for leaks. Once it has passed that test, two engineers will take three days to fit the interior. Then the car is wrapped in a strong transparent plastic foil for a day’s test driving, during which it is driven 190 miles at differing speeds up to 155mph. After that it’s into the special light room for an exhaustive six-hour check of the paintwork and finish before signoff.