From the web.
The 1967 Fiat BTM apparently is a
hard top version of the Fiat Dino.

So what we have here is a 31 year old EXTREMELY LIMITED PRODUCTION automobile.

I had the pleasure of being taken for a ride in a Fiat Dino Spider in the early ’70s. At that time the owner said it was hard to get parts. The Fiat Dino is only a small step less that a Dino Ferrari. I has pretty much the same engine as a Dino Ferrari and makes a HOT 124 Fiat seem like a tame set of wheels for Grandma.

I was a Fiat mechanic for over ten years in an independent repair shop that often got work the dealer had botched.
We also did Alfa Romeo, Lancia, Ferrari, Maserati, Saita and OTAS repairs and maintenance.

The likelihood is that the parking (so called emergency) cable had stretched and as it would only act on the rear wheels anyway was not equal to the task of stopping the car when the service brakes failed.

As for the reliability of Fiats, it is highly dependent on the level of the maintenance and aptitude of the mechanic.

I fondly remember one of my personal customers. Her ‘Marcello’ frequently paid my house payments and bought my munchies month after month. Nothing major, not abusively driven but just a constant list of minor things to repair.
Then she bought a Honda and I never saw her again!