Maybe it's not Marchionne's fault, he's the CEO of the group. I don't know exactly what each does but the Chairman is John Elkann and the biggest shareholder, of FCA, is
Exor S.p.A, which belongs to the Agnelli family(similar to Porsche family and VAG).
John Elkann is also the CEO and Chairman of this ivestment company, so maybe it's less due to Marchionne himself.
I also think we cannot overlook that VAG have an awful lot more money to "play with". FCA have to operate more conservatively, so I think it's a bit harsh to expect the same level of commintment, from them, as VAG has been adopting.
They'll be always very cool and relaxed with Ferrari in F1 because Bernie gives them ~$180M, per season(~$100 just for being on the grid, then plus the WCC prize). Ferrari also lures the biggest sponsors, in F1, so Fiat-Chrysler likely has to put quite few money, if any at all, into the team. It's a great business/ROI to them