I like FillUp's cleaner, less complicated interface as opposed to Fuel, which I've been using for a while. Having said that, I do have some wishes:
* Include the location in the "Recent" pulldown for stations. I mostly buy gas at a station about a mile away from home; it's silly to have to keep typing in the location. I do buy gas at other stations -- usually the same company -- so I do have need to not just call the one I'm close to "home" or something similar
* Allow entry of the total price, not just price per gallon. Although, it'd also be good to just pre-populate the price per gallon based on the last fillup.
* I'd also like to see an on-screen number pad.
* The ability to record maintenance, and to have an alert when you need maintenance, would be great. I'm still missing the PalmOS AutoBase program, which I'd been using since 2004, until I bought my Pre last year. Fuel's maintenance functions don't even come close to AutoBase, and of course FillUps doesn't have one (hopefully that's a "yet" ). I don't think it'd clutter up the interface much; just have a different scene for maintenance, and a way to switch back & forth from maintenance to the fillups list.
btw, I *love* the overview graphs, and using tilt to get to them is cute. I'm not sure it's really necessary to do that as opposed to a simple button at the bottom, but it is a nice display of the Pre's capabilities.