Fiat-Chrysler president Sergio Marchionne apparently tried to convince Toro Rosso to accept an Alfa Romeo-branded power unit for 2016, according to German website Autobild.de.
Marchionne was keen on having the group's iconic subsidiary enter Formula 1 as an independent engine manufacturer, but ultimately Red Bull refused to foot a bill estimated at around 30 million euros to cover development costs, which put a halt to the plan.
Toro Rosso's power will be supplied by Ferrari this year although the Faenza-based outfit will use a one year-old specification engine.
In spite of its power-unit specification lag, Toro Rosso boss Franz Tost is still confident in his team's prospects: "It's still a step forward for us."
Junior bull Max Verstappen was equally confident, claiming the performance level of Toro Rosso's new contender will increase by as much as one second a lap compared to the outfit's 2015 chassis.