@ Nutcase:
From my experience the timing is always the same and I'd say it's about 1.5 seconds, but I haven't done any precise measurements. It may not sound like much, but in a racing game it's a very long time.

@ KGB:
I still do it from time to time in the hope that it magically turns out just right somehow, and it's probably not the biggest loss in the world unless you ss off the track and have to respawn like what Saturn mentioned... worst feeling in a race ever >=(