I think the Croma's biggest problem (oustide of being a reskinned Vectra) is that it falls outside of what most people think of when they think Fiat. Fiat's core competency has always been small, stylish, efficient and economic cars. The Croma is rather the opposite. Fiat's quality reputation also did not help and I think some prospective buyers were put off by the thought of having the steering wheel come off in their hands and all the rest and didn't want to buy a car at this price level that they expected to have potential problems with.
Here in the Little Land of Chocolate and Beer, Fiat Belgium was clearing out unsold pre-facelift Cromas with a 30% discount off the tax free MSRP for those so entitled and up to 26% off on the facelifted versions. Not a good sign.
The Idea has also been a flop and it is no longer sold here. Having owned one, I can say that part of the problem is that it was too expensive compared to the Punto, the chassis and steering were poor (and that's being polite) and the big blind spots caused by the front pillars did not exactly help matters. For the rest, it was very good on interior space and flexibility and the 1.9 JTD was really fun to drive in a straight line.