The water temp rises too slowly, hitting 90c° only after 10Km (driving
about 90Km/h with 5c° outside), when temp reaches 90 it suddenly drops
to 75-80 and then rises a little but usually is always below 90c°.
Alfa uses a different way of showing the temperature compared
to i.e. Opel, Audi, VW. I guess Seat is VW so......
The difference is that in fact the temperature always goes up and
down because there is a thermostat (in all cars!!) that opens when
the cooling circuit reaches a certain temperature like 90dgr.
When the thermostat opens, a whole lot of relativaly "cold" cooling
drops from 90 to 70-75dgr.
Alfa shows this immediately on the temperature indicator whereas many
other cars measure an AVERAGE temperature that goes up and down very
slowly and certainly will not show the peaks like the Alfa way.
I guess this is done because the "normal" car driver will get in panic
and goes and see their dealer to check if nothing is wrong and Alfa is
of the opinion that Alfisti, as real, true car drivers, as enthousiastic
and knowledgeable car dirvers and can "see through" this.
So, forget about bothering the dealer, just enjoy your Alfa and keep
a regular eye on all engine fluids; don't forget the fuel tank ;-)