Here's my series of Speedrun video tutorials for those who want to learn how to speedrun this game which covers the differences as well as different strategies for each vehicle on all tracks when running Grand Prix or the Leagues/Tracks individually.

When doing individual level runs while playing on the US/JP version of the game, No Pausing allowed during PB attempts so the In-Game Timer remains accurate.

Playlist: https://www.youtube.com/playlist?list=PLgNKz5tt3CEZhZTIUbx3wEfsEZR6BCLw4