@LLL2010 since you are reporting both the properties on schedule-E , you can (a) include the mileage for property A under its expense and ditto for property B; (b) you either use standard mileage rate or you have to allocate real expenses between 1. personal , 2. Property A and 3. Property B -- you cannot use registration fees and mileage for the same asset.
Personally, I would keep it simple and use the standard mileage rate ( unlikely IRS would challenge that as opposed to actual expenses ) and bin the mileage between the two properties, especially if they are not in the same neighborhood ( but you need to have actual contemporaneous records, just in case you get challenged ) -- a daily log with dates and miles would be good.
Does this help, or you need more ?
