This is Andy, the owner of Fuelly. You might not be aware but it's expensive to build apps and provide a service for free. Fuelly has been provided free to consumers since it was launched in 2009 as an ad supported business model (similar to Facebook, Google, etc). Without any income we would not exist.
We plan to offer an upgrade to remove the ads but that will be in a later version. For now, the only option to use this free and free service is to be so inconvenienced to see a couple of ads on the app screens. We look forward to getting the ad free version released but that is still a little ways away.
As a software developer myself, I just have to ask, what in the world would be the rationale for not to include such option to the app immediately as ads were added? Fast and easy money over a little more development time and as a result happier users?
I too would have liked to support you by paying a reasonable amount of money (even yearly, like I do with some of the mapping/tracking apps I use), but no way in h*ll am I using an app with such intrusive ads (in the middle of app functionality) no matter how great the service is.
Sorry, but uninstalled within minutes of installing the app and also wrote this opinion in the review of the app.