The problem is that ship speed varies too quickly for any capture equipment I possess to register the changes adequately in order to work out the times you mention. I only have a 30FPS camera and a DVR (With severe input lag).

This will not work as during the video editing process I will be unable to decipher the numerals of the speedometer (motion blur).

Any test but the two I already have done are significantly harder to put in place than you might think.

I assure you however, the times were taken as 'tightly' as possible.
The timer started when the X button was pressed, and was stopped when the speed of 780km/h was reached. I have pretty good reflexes (Unreal Tournament player here, and of course WipEout), so I do think that I pressed the stop button at roughly the right time.