Mustangs go through the assembly line at Ford's Flat Rock plant in Michigan, Aug. 20, 2015. Ford is debuting its Mustang Shelby GT 350 and 350R models. The 2015 Mustang has surpassed the Chevrolet Camaro in U.S. sales in the first eight months of the year. Bill Pugliano/Getty Images

The all-new sixth-generation 2015 Ford Mustang’s first-ever fully independent rear suspension is a hit among the need-for-speed tribe of U.S. car shoppers. Sales of Ford’s 50-year-old original pony car have sped past General Motors’ Chevrolet Camaro, according to sales data released Tuesday, indicating Ford’s success in creating a Mustang that appeals to buyers too young to be drawn by the vehicle’s roots.

This time last year, the Camaro was the top seller of the U.S. muscle car trinity, while Fiat Chrysler’s Dodge Challenger remains in third place in unit sales, as it was last year despite a 36 percent boost first in the eight months of the year.

Most automakers release monthly U.S. sales data on Tuesday, and forecasts expect a decline compared to August 2014 because of the timing of Labor Day weekend, one of the biggest new-auto sales events of the year.

“Mustang sales increased 70 percent compared with a year ago ... marking its best August performance since 2007,” Ford said in a statement released Tuesday. Mustang sales are up 53 percent for the first eight months of the year, to nearly 87,000. The demand for the new Mustang drove Chevrolet Camaro sales down 13 percent for the year, but the all-new sixth generation Camaro, due out later this year, could challenge Mustang’s lead next year.

Fiat Chrysler Automobiles said the Dodge Challenger had its best August on record with a 25 percent increase to 5,235 units, thanks in part to enhancements made to the 2015 model year, including a new 8-speed automatic transmission and a more powerful V8 engine. But despite a 36 percent increase in Challenger sales for the first eight months of the year, Dodge’s muscle trails the Mustang and Camaro in demand.

Estimates from major automotive forecasters like, Kelley Blue Book and TrueCar Inc. predict total August U.S. new-auto sales to ring in at about 1.52 million units. The seasonally adjusted annualized rate – a key 12-month running estimate that gauges consumer sentiment and the health of the automotive sector – is expected to be between 17.2 million and 17.4 million for the month, about where 2015 total new-auto sales are expected to fall.

Last year, Americans bought 16.5 million new cars, SUVs and pickup trucks, and this year will likely be the sixth consecutive for growth, an unprecedented run fueled by low interest rates and improved economic conditions compared to 2009, when U.S. sales dropped to 10.4 million units, a 27-year low.