[ECONORAM]

How about this:
CarPal v0.91 freeware for Windows Mobile Phone.

Vehicle Manager for Windows Mobile Pocket PC by iambic, Inc. 3.5. Proactively track all your car's vitals and maintenance history when on the go.. Download and information on iambic, Inc.
[edit] found one more... http://www.giveawayoftheday.com/soft/021239/

not free, but might be worth a look:
RMRCar for Windows Mobile Downloads by RMR Software at Software Geek - Business & Finance - Personal Finance

I agree, Palm software was and is much easier to find...