Chrysler Group, a unit of Fiat SpA (FIA.MI), handily beat analysts' expectations by showing a 20 percent gain in U.S. auto sales for August, and forecast a stronger-than-expected month for the full industry.

Chrysler said on Wednesday it expects U.S. auto sales to rise 3 percent form last year, which would easily top analysts' expectations of a gain of 0.1 percent.

Analysts polled by Reuters expected Chrysler U.S. August sales to rise 12.6 percent.

Auto sales are an early indicator of consumer demand as the industry accounts for one-fifth of all U.S. retail spending.

Nissan Motor Co (7201.T) also beat expectations, showing a sales gain of 11.5 percent to 134,388 vehicles. Analysts expected a rise of 2.4 percent.

Nissan and Chrysler were the only major automakers that analysts expected to show a sales gain for August.

Chrysler said U.S. Labor Day weekend sales were "tremendous," which helped to power the automaker to a 53rd consecutive month of year-on-year sales gains.

Jeep, Chrysler's primary global brand, led the way with a 49 percent sales jump, and Ram pickup trucks, which are key to company profits, soared 33 percent.

Analysts polled by Thomson Reuters expected monthly industry auto sales of about 1.5 million new vehicles, and a seasonally adjusted annualized sales rate of 16.6 million. It would be the sixth straight month showing an annualized rate above 16 million, a level reached only twice in 2013.

A Reuters survey of analysts showed market leader General Motors Co's (GM.N) sales down 1.2 percent; Ford Motor Co (F.N) off 1.4 percent; Toyota Motor Corp (7203.T)(TM.N) falling 2.3 percent; Honda Motor Co (7267.T) sliding 7.9 percent and Hyundai Motor Co (005380.KS) and its affiliate Kia Motors Corp (000270.KS) down 0.8 percent.