Fuelly SMS app for Windows Phone
 

This app lets you send your fuel ups via text message very easily. Just choose the phone number to use (US, UK, Canada) and set up your different vehicles and text message shortcuts once and you're good to go. You can then send fuel ups very easily even without a data connection: https://www.windowsphone.com/en-us/st...6-ee58aa4eeaf5

Or you could add your tank details onto fuelly by using the mobile website. Easy enough.