Honestly, pretty simple, but it's got some cool stuff going on. I like how the meter slowly 'deflates' when you're not collecting trash, encouraging the player to always collect-- And then, when you're at high speed, collecting trash refills it, extending the time you have to go fast. This means that when the player hits fast mode, they're encouraged to try and go sicko mode and just gobble up so much trash. That's a pretty fun idea