The carmaker has also outsold Ford five out of nine months this year.
Fiat Chrysler Automobiles has been on a roll lately, its sales performance has been strong all year with a six-percent increase overall compared to 2017. Where rivals like Ford, Toyota and Honda have all seen a fall in sales in September, FCA has just posted its best results in almost two decades.
With 199,819 deliveries last month, FCA also edged past Ford's results by a narrow 2,415 vehicles. It isn't a one-off fluke either, having outsold Ford in four more months this year too.
"Our Ram and Jeep brands propelled both our retail and total sales to their highest levels in 18 years," said Reid Bigland, Head of US Sales.
Jeep sales topped 80,000 units for the sixth time this year while Ram vehicle sales reached 56,447, the highest September sales since it was launched in 2009.
Dodge sales rose the most at 41 percent and even Alfa Romeo saw a 29 percent increase in sales thanks to a strong showing by the Stelvio. Fiat and Chrysler cars, on the other hand, saw a downturn in sales but their low volumes didn't do much to dampen the group's overall performance.
Stepping aside from all the numbers and percentage figures, it is clear that FCA is currently on a sustained upward trajectory, made all the more impressive by the fact that rivals like Ford are experiencing a slowdown in their market performance.
Perhaps the move away from sedans is proving a bit premature or maybe the latest Jeep and Ram products are proving to be just what US shoppers are looking for.