Brian,
You're absolutely right about the default behavior for 'mileage' handling.
First, let me clarify that OpenHealth Service (OHS) Plug-ins do not affect the default behavior of the HealthFrame Explorer application. In other words, the plug-ins may be designed to interpret data in a way that is above and beyond that of the default design.
This is the case for 'mileage'. HealthFrame is treating 'mileage' as it would other dollar-based expenses such as co-pays, premiums, etc: it expects all expenses to be directly (without conversion or multipliers) monetary in nature (i.e. $ in US). The OHS Plug-in is really designed for the purpose of tax-related calculations, as specified by the IRS.
What you want to do is to use the OHS plug-in for the medical mileage-related expenses (which is 'smart enough' to do the mileage to dollars multiplication) and to use the customization feature to filter out the mileage data from the built-in reports (see image below).
Thanks,
Support Team