If you remove a vehicle from the Automatic Classic app, then the data associated with it is also removed. If you still have access to the vehicle you can re-install the adapter and the trip data will reappear. Open the Automatic Classic app and go to the Settings menu. Tap on Setup Another Vehicle and follow the in-app instructions from there. You can have multiple vehicles installed on one 2nd Gen adapter. If you don't access to the vehicle, then the data isn't retrievable, unfortunately.