What influences the number of fans I get per race?

In Grid 2, the mechanic to move between racing leagues is the gathering of "fans". You seem to get a number of fans for taking part in each event and from completing sponsorship challenges.

Is this number of fans per event a fixed number or is it influenced by things like the position you finish in, how far ahead of the competition you finish, et cetera, or is it just a specific number of fans per race regardless of overall performance?

Are there any other methods of gaining fans?

I find that placing first in a race will get you all the fans that are available for that race, regardless of time difference, your sponsors will get you the number of fans that they say when you are picking them at the beginning, (where I am it's 13,000) and you can find out by looking at the event (by going to events> season> [the club you want to compete with]> [the event you want to compete in]) and then waiting until Callahan says something like: "You can show 65,000 fans what the WSR is all about at [Name of City event is in]. That's it.

Good luck!