Race day has started - I haven't recorded details, but I have won M$ 65,500 for completing day 1,  with M$ 15k bonus completion reward.

Note:
Car has three hour window of free/instant servicing and three hour window of instant upgrades after completing stage 1.
The event also allows you to start day 2 immediately (unlike 720 Degrees where it was locked until the next day), so it looks like completion may be possible in one sitting if you have the time...

Good luck all