Hi vanbt7,
Good day!
We're sorry for the inconvenience this issue have caused you.
Currently, there is no way to update the mileage after first finding the value. The user cannot update their car details (we assume your car's properties never change).
You'll need to manually update it moving forward or add a new Car in order to correct it. Moving forward, Mint should refresh the car value every Thursday night or Friday morning based on Kelley Blue Book.
If yours didn't update, let us know immediately.
Thanks,
Mint Steph