Xenon Racer

This can be done solo. Go to the online mode, create a lobby, and press X to edit the lobby settings. You'll need to add in two other races, by pressing RB to add more races. You'll be racing against the AI.

I picked USA as the location, Boston Port(Boston Port wasn't available the first time I played the game, but it unlocked after I played my first online race solo, even though I got last place), one lap, and sunny, based on the suggested setting from Themanzack's guide for World Champion. Then just copied those settings two more times, so it would be three total races.

At the end of each race on the results screen, you can press X to see your total score, to see where you are currently ranking for the total numbers of races.