To my mind these GP events look like as one big fat mistake. If I could make 00.39... on the 5th round, some polish racer (1st place) made it for just 00.36... Should I even try to compete with him? Nope, there is no chance at all for a player like me.
4/5 of the Windows players are playing GPs just for small rewards offered in between.
As to the problem mentioned above - yes, I've met such GL tricks before. They are like this:
1. my car suddenly lost the speed right before the finish line
2. my car after the take off the ramp and touching the ground by all 4 wheels when landed suddenly exploded
3. my car started to run in wrong direction
4. the time left suddenly started to run faster right before the finish line
5. for some reasons the opponent's car is flying the longest distance than my and running faster on the straight way (even when I use full nitro and shockwave)
So 3 attempts given are not enough to show the best times we can make.
It cann't be difficult to be honest with your teammates and with yourself.