ppc logbook

Hi

I need advice on how to make a log book to keep track of my car's fuel consumption.
To be run on a ppc or wm6.5 phone
For example when I fill up with fuel, I want to be able to add the Liters, Price, Mileage, Date...
and whenever I want, press a button to display a file (txt, or excel...) with all the recordings.

Any pointers?

thanks