Levels were introduced in the 0.6.0 update in 2021. Since then, there have been many updates to the levels and the maximum level in Smash Karts is now 200, at 5 730 000 XP.

XP is earned by playing games and smashing karts. Each game earns you 100 XP (300 if you have 3x), along with 10 XP (30 if you have 3x) per player you smash. Collecting a Gem or Candy in Gem Collector or Candy Rush will give you 5 XP (15 if you have 3x). 

The following is a table that includes every single level, the XP required for it and the rewards given out when reaching each level.