Gas Cubby 2.7 broke all history data collected for several years
All data earlier than May 2014 got screwed up. It looks like total cost was left intact while cost/litre and litres are invalid (cost became smaller while litres count proportionally increased). All this resulted in incorrectly high L/100km data. I've seen another report about incorrect gas consumption values in this forum.
Fortunately I've got a CSV data exported on 18th of September, 2014 with correct values but currently the synced data is broken for me.
The default unit setting in Gas Cubby is MPG (US), which means it takes miles and US gallons for input and then outputs miles per gallon. You likely have been using Gas Cubby with other units but, when your data was lost, the units were reset to the default MPG (US). Online Sync only stores the numbers, not the units, so the proper numbers were downloaded but you changed the units back to the proper units setting after the data was recovered, doing a unit conversion in the process.
To fix this, do the following:
Note: if you have not tapped Sync since recovering the data and changing the units, you may skip to step 4.
1. change the units back to MPG (US)
2. go to the Setup/Login screen and tap Delete Synced Data
3. return to the main screen and tap Sync
4. return to the Setup/Login screen and tap Delete Local Data
5. change the units to what you had been using all along
6. return to the main screen and tap Sync.
All your data should now be properly restored.
While it may be difficult to have incorrect old data sitting on your device, is it possible to bare with us while we work on the Gas Cubby/Fuelly integration? Once we can get sync finalized you'll be able to edit your data and then import it into Fuelly and then have GasCubby sync with the correct data.
Unfortunately, we do not have the ability to force data onto the sync server in the way you're proposing.