In complete disagreement with the new proposals for technical regulations of Formula 1 which wanted to prohibit the use of V12 engines, in 1986 Enzo Ferrari threatened to leave the category to devote himself to the American Formula Indy (500 miles of Indianapolis and the Cart Championship). And he was not satisfied with announcing the withdrawal of Ferrari from F1, but also had a car built in compliance with the Cart regulations, the 637, equipped with an unprecedented V8 turbo. However, the F1 regulations were not touched, so Ferrari continued to use its V12s and the 637 project for the American program was shelved.