No MG is taking part but there are competitors in MINI and Great Wall...
http://www.dakar.com/dakar/2013/us/rider/rider-list-cars.html#ancre
starts in one MG country (Peru) and ends in another (Chile). Don't think they can make a lot of sales on Britishness in Argentina... http://www.dakar.com/dakar/2013/us/route.html