IKCO manufactured 145,045 vehicles, registering a rise of 37.7 percent compared to the same period last year, IRNA reported.
SAIPA produced 109,258 vehicles in the said period, 7.2 percent less than the figure for the four-month period of the previous year.
Pars Khodro also manufactured 35,008 vehicles in the period under review, 5.6 percent lower than the figure for the same time span of the preceding year.
IKCO, SAIPA, and Pars Khodro manufactured 900,714 vehicles in the previous Iranian year (ended on March 20), which was 4.3 percent more than the figure of its preceding year.
The Iranian Ministry of Industry reported a 19.1 percent surge in car output for the last Iranian year.
It expects output would increase by over 21 percent this Iranian year to 1.2 million units.
Iran has seen a major boom in its homegrown automotive industry in recent years as major international brands have almost no presence in a market affected by US sanctions.
Experts say the increased output has become possible thanks to growing investment in local manufacturing of auto parts that used to be imported.