The Argentine battled hard with Sergio Fuentes and Andrea Mazzocchi throughout Friday, and ended the first full leg with just 11.3sec in hand over the latter.
However, Mazzocchi was dealt a devastating blow when a 50sec time penalty dropped him out of the lead scrap.
Soria proceeded to stretch his advantage on the final day by winning four of the six challenging asphalt speed tests and secured his second victory of the season by 45.1sec from Fuentes.