That depends how hard the car is still accelerating in that 1 second. From GPS logs back in 2010 when I did mine at Woodbridge,
My car is well off the boil at that point, but even in the 1 second to 200mph, I gained 2mph.
ie 198mph to 200mph was 1 second.
Some cars still accelerating much harder would be gaining a lot more
In the 1 second prior to 190mph I gained a 3.9mph.
1 second prior to 180mph 4.6mph
Datalogs from this year at Elvington, car going much better, but still room for improvement
It was only 1km, so will only sue the 180mph time and 1 second prior it was 7.1mph gained in 1 second and covering 78m
So every little bit of extra distance and time does matter.