Ford Motor’s new 2015 Mustang has surpassed the Chevrolet Camaro as the country’s best-selling muscle car, according to industry sales data released Wednesday. And Ford says demand for the sixth generation of the iconic pony car is increasingly coming from younger buyers who are less obsessed with engine size and more willing to adopt newer turbocharged four-cylinder engine architecture that pumps out horsepower with less gasoline.

Through June, American buyers drove over 68,000 Mustangs off dealers' lots, thanks in part to increasing numbers of millennial-age buyers--people in their 30s or younger. That compared with more than 42,000 Chevrolet Camaros in 2015. This time last year, Camaro topped Mustang in sales. If Mustang retains its lead, this year will be the first time since 2009 that the Mustang has overtaken its main rival.

Sports car sales are one of the few interesting developments in the car segment, defined as vehicles that aren’t SUVs, crossovers or pickup trucks. While sedan sales are losing ground to other body styles, sports and luxury car sales are growing. “The sports cars, like the Mustang and Camaro are the only bright spots in the car part of the market,” Michelle Krebs, chief auto analyst at Autotrader.com, said in a conference call Wednesday.

Both Ford and General Motors have re-tooled their muscle cars to appeal to younger buyers. Gone are the days of luring middle aged Baby Boomer males nostalgic of the days of the big grumbling engines of their youths. Younger buyers want modern interior features (think: smartphone connectivity and touch screens) and fresh design cues. Perhaps most significantly, millennials in the American muscle car market are embracing some of the hidden disruptive technology beneath the hood.

Ford’s 2015 Mustang offers an optional a 2.3-liter turbocharged Ecoboost four-cylinder engine. Though the “eco” makes it sound wimpy, the small engine puts out 310 horsepower while getting 32 miles a gallon the highway – specs that would have been impossible just a decade ago. The V8 engines still make up over a third of Mustang sales, but clearly all automakers are planning for a day when V8 passenger cars might be phased out completely.

The 2016 Chevrolet Camaro that comes out later this year will also offer a smaller engine than its current fifth-generation model, a 2-liter turbocharged four-cylinder pushing out 275 horsepower and more than 30 miles per gallon on the highway. Both cars are lighter than their predecessors as automakers work to meet more stringent government fuel economy standards. The new sixth-generation 2016 Chevrolet Camaro will likely steal back some market share against Mustang, but for now Ford is riding high on strong demand for its latest racing pony.