Spreadsheet + Graph of average km's

Hey,

Currently I am stuck on the layout of a spreadsheet to capture and predict servicing of fleet vehicles.

To explain further,

I have been given the task of looking after out work fleet vehicles, maintaining cleanliness, servicing, damage reports etc, etc.

On a weekly/fortnightly basis I collect the current km's and note them down, record any damage, book them in for scheduled service's etc etc.

What I would like to do, is have a sheet per vehicle(or all on one if I can), then have a summary sheet, with a graph/graph's, that will plot the current up to date data(km's) with the data and then also using the data to plot an estimated date/week that vehicle will require it's scheduled service.

Any advise would be appreciated.


Edit: I should add, the maximum lease is 24 months and and 60,000km's. The attached sheet, is the average km's per month(this is keep by a different person and is statewide). But something like this would be great.