I can see how a Mileage Tracking feature in the QuickBooks Online International version would be beneficial to you and your company. We are unable to provide a specific time frame for when this feature will be available.
After that, QuickBooks tracks these bills in your mileage expense account. You can go to Reports, then run a Profit and Loss report. All of the expenses are listed in your mileage expenses account. Once you have a report open: