I find that my 2C is fine with modern traffic - it buzzes along at 70-75 on motorways without any problems
Following from Wikipedia.
Berlina 2C (Tipo 818.100/101): 1964–69. Improved, more powerful Berlina launched late in 1964, with a 71 bhp (53 kW) engine fitted with double twin-choke Solex carburettors. The body-shell also had revised front subframe mountings. Distinguished by an enamelled "2C" badge on the radiator grille and rear "Fulvia 2C" script.
Berlina GT (Tipo 818.200/201/210/211): 1967–68. Introduced at the 1967 Geneva Salon with the 1216 cc (later 1231 cc) engine from the Coupé, producing 80 bhp (60 kW) at 6000 rpm.[4] Distinguished by an enamelled "GT" badge on the radiator grille and rear "Fulvia GT" script.
Berlina GTE (Tipo 818.310/311): 1968–69. Introduced in 1968 with the 1298 cc (818.302) engine from the Coupé Rallye 1.3, for an output of 87 bhp (65 kW) at 6000 rpm. In addition the brakes were uprated with a brake servo.