These are some very cool additions. I especially adore the rocket car. I adore it so much that I seriously seriously wish there was flatter terrain where I could get speed, skid around with a brake key, or traverse through a small city with roads. I'm very eager to see what you end up putting out in the juice fog later down the line. I'd love to make a high-stakes trek out to monster level 500 and find a big city with new creatures that stalk me or something wild and unique that throws the gameplay for a loop.
Just some functionality feedback though: It's possible (and also extremely fun) to point the car straight up and begin boosting, which provides enough thrust to begin flying upwards. With careful orientation control via spacebar so as to not slam into the ceiling and ruin your vehicle orientation and also not lose too much height and accidentally crash-land, it's possible to raise one's horizontal speed to staggering numbers (many times faster than max-upgraded player flight speed) to the point that when you do eventually hit the ground again, you're going so fast that you actually phase through the ground, the camera bugs out, you're staring at the void, and there's no recovering from it other than returning to main menu and loading game. This happened to me multiple times because I was having so much fun trying to see just how fast I could go if I was able to remain airborn for as long as possible.
One thing I noticed that was very annoying, there's clearly some invisible barrier when you go high enough that transitions to a new playspace. Trying to bring an enemy with you that high via the kinesis wand results in the enemy disappearing but the magic link not breaking, and when the car goes high enough, it 'bumps' into this zone and alters the vehicles orientation significantly. Dunno what you could do about it seeing as I'm almost positive it's to allow the transition to and from spaces like the overworld to school, or overworld to underworld plane, but if there's a way to eliminate the jankiness of that transition, that would be really ideal. Especially for down the line if perhaps you wanna put aerial enemies and give the player a helicopter or something and then have unique little planets or floating locations at like 100+ monster level out from spawn or what-have-you.
Overall though this is some really fun new stuff, especially the car. Definitely keep going in the direction of switching up gameplay for even further player-freeform-engagement features and content.
I really wish I could upgrade that car, but at that point I suppose, more practically, I'd just want more vehicles instead. Though, a rocket car that boosts me to monster level 1000 in 30 seconds and then glitches me into a softlock abyss still sounds fun and bananas, lol. Still though, extremely fun to play with even aimlessly and without real purpose. Hope a discoverable race track or a monster truck boss in a big flat arena or something is in your list of ideas. Car is amazingly fun, and thus, needs more in-game purpose sooner rather than later.