A rough prototype of the 4 pages is below (or at gomockingbird). Any feedback is welcome, either in the comments or by email.
Landing PageThe landing page should answer the questions "Why?" and "How much?" as well as addressing the risk of putting data into a new service. If you can export the data right away, there is little risk of losing your work.
I want the home page to give me an idea of what should be coming up, and easily let me record what I've done. The fewer clicks, the better.
The estimate of what the service will cost is based on previous data. In my experience "How much is it?" is always the first question someone has about oil changes, and it's helpful to be able to know this right away.
Just a simple place to see the history of each car. It should be easy to print off a copy when trading-in or selling to private party. Detailed auto records often fetch much higher prices for used cars, and the system can do this for us easily.
Add a Car
Eventually, the details of the car can pull a recommended maintenance schedule, useful for creating reminders on the home page.