Each twenty four hour period you will see an icon over the main menu icon which has an envelope with money in it. Tap on this icon as it allows you to send an email, text, or tweet to two friends inviting them to play the game.
You will earn a bonus for each of the friends you send an invitation to and the icon will disappear until the next day.
Be sure to take advantage of these surprise bonuses as they tend to be very large and are frequently cash prizes.
As for XP points:
Each time your car goes to work it will earn money and XP for you.
Each time you upgrade your car it will earn money and XP for you.
Each time you put fuel in your car it will earn money and XP for you.
Each time you put new tires on your car it will earn money and XP for you.
Each time you win a Grand Prix race your car will earn money and XP for you.
Explore the galaxy in the franchise's first open-world game.
