In the U.S., FCA Sales:
Performers
Jeep sales have incresed from just over 231k in 2009 to over 828k in 2017.
Ram Truck sales have increased from 213k in 2010 (spin-off year) to over 556k in 2017.
Ferarri sales have increased from around 800 in 1998 to over 2,500 in 2017.
Maserati sales jumped from around 4,800 in 2013 to around 13,700 in 2017.
Alpha Romeo sales went from around 90 in 2017 to over 12,000 in 2017.
Laggers
Fiat sales have declined from a high of 46,000 in 2014 to around 26,500 in 2017.
Dodge sales have declined from 1.2 M in 2003 to 383k in 2010 (Ram spin-off); Increased to over 600k in 2013, but steady decline to 447k in 2017.
Chrysler sales have declined from 649k in 2005 to 188k in 2017.
Of note though, Toyota Camry, Honda Accord, Nissan Altima, Ford Fusion, Chevrolet Malibu, Hyundai Sonata, Kia Optima, and Volkswagen Passat have increased sales, or are on par, from 2017 to 2018 (through March). So, cars aren't dead for all mfrs, just for some.
I doubt that it is a "brand" thing, but more of an "offering" or "styling" thing. People are buying more SUVs, Crossovers, and Trucks. Its the trend. If Chrysler/Dodge had better offerings then I believe people would buy them.
And yes, Maserati's are crap, they have problems. So does Alpha Romeo. Its a matter of time before reliability take precedence over shiney.