I have used gas bunt for years on an iPhone 5, recently got a 6 plus and attempted to transfer all the data to the new phone but when I sync, my data comes over to the new phone but the vehicle info is gone, it causes all my data to be bunched together under all vehicles. I believe I have 5 or 6 cars setup but that info doesn't come over.
In hopes of fixing it, I go the iPhone 5 and delete sync data, then try to re sync. When that is done, I go to the iPhone 6 and try to sync. Every time I do it I get fuel and service records but no vehicle data. I have an iPad 2 as well and the exact same thing happens to it. I am running the latest version of the app on all devices. I need help adapt as I need to turn my old phone into the company I work for. Let me know, thanks.
Sorry you're having trouble!
On the iPhone 5, with the correct data, please take a backup and send yourself the backup file. Also, could you try changing the sync email? You've done right so far, deleting the sync data and refreshing it with new data, but let's take it one step further and sync the current data to a new email address (account) and then use that new email to pull down the data.
Whatever you do, please do NOT delete local data on your iPhone 5. At least not until you've ensured proper sync to your new devices.