That's an iOS issue, not an issue with the app. This has happened a number of times to me in the past several years with the iPhone and iPad. You're better served posting this to the Apple help forum than to this one.
Just an FYI - We have another update coming out soon. Your data is safe. Please be patient and understand the crash was related to a fix we put in place for iOS8 that resulted in a crash on certain hardware for iOS7. Once again your data is safe and Gas Cubby will work properly soon.
LOL, have no other choice but to wait since there is no way I can delete the nonresponsive "waiting" iOS 8 icon. Pressing and holding it just brings up the delete "x" for all other apps - but not "waiting" - which is the new Gas Cubby Icon. Hard reboots haven't worked either.
Interestingly, the old Gas Cubby icon can be opened in the update section of the App Store. That has allowed me to capture screenshots of my mileage and service logs for the past two years in the event I have to manually enter that information in another app, should the current fiasco not be remedied.
I've read through the threads listed by RobertV. Have tried some of the suggestions with no success. Will work on others later this evening.