Here's a screenshot of my maintenance plugin i threw some time into today. in this example i set my oil change interval to 5 miles. the content in the message box is pulled from an .ini file thats formatted like so.
You can see at the top of the shot the total distance is 5.97 miles traveling, thus i got a warning letting me know i was .9 over my oil change interval. Once complete, the plugin will allow you to add maintenance items at runtime and view each item in list form. Selecting an item in list will show you the details from the ini along with handy labels for distance to interval, last "change" date, and time remaining.
/USER CONFIGURABLE SETTINGS
/<ITEM#>=<NAME>,<MILEAGE INTERVAL>,<TIME INTERVAL (DAYS)>,<COST(WITHOUT'$')>,<NOTES>
Maintenance1=Oil Change;5;180;17.50;Use 5W-30
Maintenance2=Air Filter;12000;360;12.00;Check cabin filter