To Excel as xlsx?

I am currently running a named query that gets exported to excel using system.dataset.exportExcel which works but can only currently export as an xls file. Is there a work around to export as xlsx file?

As of 8.0.7, system.dataset.toExcel() and system.dataset.exportExcel() have support for and default to xlsx. If you are on that version or higher you just need to make sure you are saving the file with the xlsx extension.