So basically, when you bring the phone inside the house,
out of the range of the ELM327, [and restart the app later, ]
you can see what the last data values were in the car.
I agree, a nice feature, but perhaps an option in the Settings,
with a button to erase the saved data, to start "fresh"?
Also consider saving all the CAN Messages in a log file,
with the title YYMMDDNN.txt (or ".can" or ".evc" if the
file is binary CAN-Do compatible). The NN is just a 00
to 99 sequence number for each drive of the day.
Having second, and possibly even millisecond time stamps
on each message would be helpful.
Then, one could add a Playback function (like the CANary
already has) to be able to review the data for each drive,
and have complete "Black Box" records (if enabled).
One could even set a retention limit of N days,
with 0 meaning no limit.
Inserting an micro SDHC card (perhaps 8GB or 16GB)
would give plenty of space for many days, even months
Playback could have a speed control (about 20x down
to 0.1x), with a Pause, Resume, Restart, Loop, Mark A,
Mark B, Play AB, and Loop AB.