Certain features - such as mileage tracking - are seemingly not available to users in Ireland. Is that correct, or have I missed something glaring?

Hello, @ballyreddin-bamb.

Currently, the mileage tracking feature is available in the major regions such as QuickBooks Online US or UK. Rest assured, our product development team reviews all the feedback we receive to ensure we’re meeting the needs of our customers. 

In the meantime. you can check for any supported third party that supports the feature you're looking for. Also, you can track your car or vehicle-related expenses in QuickBooks. 

Lastly, I'd recommend browsing our QuickBooks Blog so you'd be updated on the latest feature releases and product updates. You can read through this article: The QuickBooks Blog.

Get back to us here if you have other questions. I'm always here to help.