MILAN, May 15 (Reuters) - Italy's Istituto Finanziario Industriale (IFI) , parent of the holding company behind automaker Fiat , posted a 30 percent quarterly profit rise on Tuesday, in line with gains at the holding. IFI said in a statement its consolidated group net profit totalled 54.2 million euros ($73.41 million) in the first quarter against 41.5 million euros for the period a year earlier.