It was Emma. At first she didn't realize the charred, burning pile of metal was her second dirt bike but because her crush on Jesse was so strong she took it well after he revealed it.
"Here Jesse, use this one. It's identical. They will never know."
Jesse hopped on right away. "But I can't leave you here Emma"
She hopped on the back and gave his big belly a hug from behind, happy to be close to her dream man. "I'm ready for our race date Jesse. Let 'er rip!"
I watched those episodes when they originally aired and I didn't even notice at the time. (I'd make a terrible detective....lol) There was no social media so I never knew it until I heard it here.
When I was a kid we used to watch this cartoon on Disney channel and there was a "magical baby" then the next episode they were making statements like "Who did it then Ron the baby?" Im like we just saw the kids magic. Another victim of the machete order. There's actually an episode where they jump the road runner and keep mentioning daisy wanting to hurt them if they mess it up. FORESHADOWING what was gonna happen in what was intended to be the next episode but the executives denied it lol. This is also why we see Rosco and his replacements come and go. Like lester, than Rosco's, than the other guy, then back to Rosco again.
In season 2 Daisy's Road Runner is destroyed and then comes back without explanation in episodes after before the season ends. This is due to what is known as a "machete" order. Where corporate executives try to dictate the order of episodes based on what they think would be more popular instead of letting them air in the order intended.