The last I saw on the news was them showing the license plate and assuming it was left near the airport, or somewhere in Philly. I didn't think they found it yet, but I may have missed something.
This is all that I've seen so far:
"On Tuesday, Allentown police again said they are attempting to locate Esterly’s car, a red, 1999 two-door Honda Accord with the license plate KTL0529, which they believe may be in the Philadelphia area."
From the same link posted above:
http://www.mcall.com/news/breaking/mc-nws-allentown-teen-runaway-amy-yu-update-20180313-story.html