DETROIT (Reuters) - Poor sales of the compact Dodge Dart led to a week of layoffs for 325 workers at the Fiat Chrysler Automobiles (>> Fiat SpA) plant in Belvidere, Illinois, a company spokeswoman said on Wednesday.

Dart sales are down 33 percent so far this year for the first jointly designed vehicle in the Fiat-Chrysler marriage, built on the same architecture of the Alfa Romeo Giulietta.

In 2014 results through February, Dart fell to ninth place among compact cars in the U.S. market, from eighth place last year, overtaken by the Forte from Kia Motors Corp (>> Kia Motors Corporation). Toyota Motor Corp's (>> Toyota Motor Corp) Corolla, the most popular compact car, has sold nearly five times as well as the 10,000 Dart sedans through February, according to Autodata Corp.

The Chrysler spokeswoman would not give production cut figures at Belvidere, saying only that the temporary layoffs were meant "to balance vehicle supply with current sales demand."

The plant, located about 70 miles northwest of Chicago, has about 4,500 employees.

Dennis Virag, president of the Automotive Consulting Group in Michigan, said Chrysler is struggling to sell the Dart because it lags competitors despite improvements over the previous model, the Caliber.

"It's a good-looking car, but it's under-powered. Dodge is just not a brand that's in the minds of the customers when they go out looking for a small car," Virag said.

That was a perception Chrysler hoped to change with the Dart.

Gary Brown, a Long Island, New York store owner who heads the Chrysler Dealer Council, said a relatively late model year change has left an inordinate amount of 2013 Dart models on dealer lots.

Auto sales website AutoTrader.com shows there are twice as many 2013 models of Dart on dealer lots as 2014 models.

Alec Gutierrez, an analyst with industry research firm Kelley Blue Book, said Dodge in February increased the average incentives discount by $400 from a year earlier, to $2,200 per vehicle.

Before incentives, the Dart retails for about $17,000 to the mid-$20,000s.

(Reporting by Bernie Woodall; Editing by Richard Chang)

Stocks treated in this article : Fiat SpA, Kia Motors Corporation, Toyota Motor Corp