It work for me for all type of columns (string, date, numeric, etc.) But I use this from VFP.

>>This should work:

loExcel = CREATEOBJECT ("Excel.Application")
>>...
>>loExcel.Columns.EntireColumn.AutoFit()

>
>After more research on this, this option is only supported for datetime and numeric values. This cannot be applied to string values.
>
>Note also that I am doing everything in XML, thus some of the functionalities may not be supported.