I was just thinking about the blue shell. It’s given to someone in 7th place, but it doesn’t help them get ahead. It just shuffles the order of the first 3 players.
Sonic &AS Racing had a much better blue shell: A player that’s behind gets the “Hornet Swarm”, which places a network of traps at the front of the pack, slowing down ALL players by a bit. You can navigate it if you’re skillful, and if the first player hits one, the others have fewer to deal with. And of course, when the thrower reaches it, they lift up for them.