However, both cars retired and Giotto was left to focus on the forthcoming 24 Hours of Le Mans that would be held, as normal, in June. Although having originally intended to field a team of three A3/C's for the big event, Bizzarrini only managed to get chassis B 0222 onto the grid after being forced to drive it all the way from Livorno himself. Nevertheless, the French pairing of Baron Jean de Mortemart and Regis Frassinet made the boss's overnight journey well worth it when they secured arguably Bizzarrini’s finest ever competition result. After 24 hours of gruelling racing, their plastic-bodied A3/C came home in ninth overall and for the second year in succession, had taken victory in the over five-litre class. No doubt spurred on by the A3/C's historic back-to-back success at la Sarthe, Bizzarrini entered two cars for the Rheims 12 Hour race two weeks later, Baron Mortemart and Frassinet back in their Le Mans winning A3/C whilst Noblet and Mario Cabral of Portugal were in B 0207, the car that had won at Le Mans the previous year. Rheims was not a success, B 0207 retiring with clutch problems and B 0222 a blown head gasket. But something much more serious was brewing that would have serious implications for the A3/C's future on road and track.

Despite the undoubted potential demonstrated by the A3/C during its eighteen month competition life, relations between Renzo Rivolta and Giotto Bizzarrini had broken down to the point that, by August, their association was finally terminated. While marketed at the expense of Iso, Giotto had supplied nearly all A3/C's with Bizzarrini Livorno badges, this after registering the Grifo designation for his own use. Understandably, Iso were a little disgruntled and the two split, Rivolta acquiring the rights to the Grifo name for use on his forthcoming A3/L while in return, Bizzarrini was given enough component parts to construct fifty vehicles and the sole rights to build the A3/C. Now that Iso would not be funding his competitive aspirations, Bizzarrini began diverting the attention of his Livorno factory more towards road car production. However, chassis B 0222 was wheeled out for August's Mount Dore Hillclimb, ex-Ferrari Grand Prix star Maurice Trintignant taking the wheel and finishing an impressive second in class.

August also saw the A3/C's make their final works outing for the year, this at the Austrian Grand Prix GT Support Race where B 0222 and a new car, B 0226, were entered. B 0222 was driven by Kiwi, Chris Amon, who would go onto drive for Ferrari in Formula One, but in the meantime he finished fourth at Zeltweg, this having been the fibreglass-bodied A3/C's last competitive outing. American sports car ace Bob Bondurant took the wheel of B 0226 on its one and only international outing and, having been hampered by obtrusive bodywork, did well to finish seventh. Over the summer, Bizzarrini had sold his '63 Turin Salon prototype to Pierre de Siebenthal, the Swiss privateer actually being the sole entrant competing in an A3/C during the latter stages of 1965. He managed a 21st overall and fifth in class at the Ollons Villars Hillclimb in Switzerland, an unsuccessful trip to Africa during November ending in disappointment. Siebenthal must have gone to the Angolan Grand Prix for GT and sports cars with high hopes, but he retired after a promising start. So it had been an up and down year for Bizzarrini, his new A3/C's having been destroyed in their very first race whilst Rivolta also pulled the plug on their collaboration. However, there was always Le Mans to look back on.