Although not an automated solution, you can do this pretty easily with Excel. Just import the data and perform a Text to Columns conversion. This should give you two columns of data. Assuming they start at the first row and are columns A and B, set the C column to the following formula:
="<marker lat="""&A1&""" lng="""&B1&""" label=""Car "&ROW()&"""/>"
Autofill the formula down for all the rows. This will give you the marker elements, which you can just copy out into a text file, surround with the <markers /> element, and save as .xml.
It would be even easier if the file was a CSV, you could then just open it up in Excel and do the formula conversion. If you don't have Excel, you can use OpenOffice or even Google Apps to perform the formula conversion.
Let me know if any of the above does not make sense.