In 1964 the Abarth had already developed the Fiat 850 sedan, equipping it with an 850cc engine but brought to 42 and 53 horsepower (OT850 oltre 130 / OT850 oltre 150). In 1965 Abarth mounted the well-known 982cc engine on the 850. The OT1000 also weighed about twenty kg less than the OT850 and this guaranteed decidedly interesting performance for the category.