But on the other hand, I am the winner of the biggest race this side of the galaxy has ever seen, the Ile de France race of the Gallic Grand Prix.
As such, I have certain observations to make about your event here, which I believe I'm entitled to do.
First of all, you can't give out such a humble prize when you are asking ten millions for each inscription. You will definately have more than ten racers there, so instead of racing this would be business for you.
Now, why do professional racers want to have the impression that the organizers are not doing it for the money? Well, being a rally as you describe it, and saying in the terms and conditions that you are not responsible for the racer's fate during the event, one may be suspicious about the whole thing.
I assume you are getting an income elsewhere with this race too, namely sponsors and such, so you should definately make the prize exceed the total registration pot. That way, serious racers as myself will consider taking part in the event, making it more prestigious with their presence, and thus attracting even more racers, public, and press.
So... what will it be? Raise the prize or lower the registration fees?