Best races to grind XP wise (level 20 or lower)?

[ghsnu]

Stuck at about halfway to level 21 and wondering what's the best race to grind for XP?

 

[moneyfink]

There are lots of XP to be had in these events. They are also quite fun and rewarding:

Flight Academy Mercedez Benz AMG under specials events
Rally gran turismo under special events

They can only be done once, but they are quite XP loaded for level 20/21.