I'm 98% sure that you can shave 1.5 or 2 full seconds off the time, though. It's been a long time since I played deathrace (best is about a 45 second time, not tool-assisted), but I'm almost completely sure that if you fall off the course and accelerate to your death ASAP the clock stops as soon as you die, saving a little time because the clock is no longer running while waiting for all the enemies to finish dying and the game to declare you a winner.
Just by quickly watching the vid and pausing, it looks like at about 6.8 seconds you have all 29 stars and are very near an open edge.
I realised this just after I posted the video so I edited the movie description. I modified the ending to get a time of 6"993. Time could still be saved elsewhere. If I could manipulate the drivers better I wouldn't have needed to slow down at the end to kill the drivers behind me. The time could probably go under 6 seconds this way.
Could someone do a GP run that destroys all drivers every race, to get 174 stars at the end? That'd be pretty spectacular to see - aims for highest time while destroying all other racers.