The Hellcat is a triumph of engineering bravado over common sense, a Hemi V-8 so powerful that eyeballs rolled when Dodge announced the engine in 2014.

Seven hundred and seven horsepower? Yeah, right; maybe for 10 to 15 seconds, before nanny software stepped in to protect the engine. I wasn't sure Fiat Chrysler would actually build the Hellcat, but if it did, I expected the car would be completely undriveable, cost $100,000 and be the latest automaker stunt engineered to win the news cycle, not a drag race.

Wrong, wrong, wrong and wrong.

Two years later, the supercharged Hellcat V-8s have become an icon for the whole Dodge brand, starring in raucous commercials and posters on teenagers' walls in a way not seen since the original Charger lifted Dodge from suburban bland to outlaw chic 50 years ago.

Fiat Chrysler has sold more 15,000 Hellcat powered Charger sedans and Challenger coupes, far more than it expected. Some customers waited more than a year to get their Hellcat, even after Fiat Chrysler doubled production.

As the vehicle market turns away from sedans and coupes and buyers flock to SUVs, modern muscle cars like the Hellcats draw loyal, enthusiastic owners. Across the industry, sales of traditional passenger cars are down 8% in 2016. Hellcat sales are up 8%.

There's something more than a little crazy about setting out to make a 707-hp street car that cost $58,295, as the 2015 Challenger SRT Hellcat did when it hit the market last year, but crazy may be what Dodge does best.

"It's emotionally raw and exciting and that's just what Dodge needed," IHS Automotive senior analyst Stephanie Brinley said. "It came along at just the right time."

The first rumblings of the Hellcat's thunderous exhaust were heard in 2011, when Cowland's team approached the corporate product forum, which includes CEO Sergio Marchionne and 20 top executives.

"You can bring any idea to the product forum," Cowland said. "If you can make a business plan, you can plead your case."

The original target was 600 horsepower, enough to make the Hellcat the most powerful muscle car, displacing Ford's Shelby GT500 Mustang. No sooner did the team tell the product forum it had succeeded than word snuck out that Ford was working on a Shelby GT 500 Mustang that would top 600 hp.

The product forum wasn't playing for second place, so Cowland upped the ante. His team would deliver a 675-horsepower engine.

The bosses said OK, but the team got no extra time for development, and they had to deliver the same fuel economy they'd promised at 600 horsepower.

"The timing was a real concern," Cowland said. "Internally, the team's target had always been 700 hp. We like to over-deliver, but we'd expected more time."

Even some parts of the product development team didn't know the powertrain team was working on a 707-hp engine. The horsepower tests were verified by the Society of Automotive Engineers – the gold standard of engine certification – but the numbers were never released within the company. It was Fiat Chrysler's Manhattan Project, so secret that people working on one part didn't know what those working on another were doing.

"There's a moment of clarity when you accept who you are," said Kuniskis, who is the head of FCA's passenger car brands in North America. "Customers liked the fact that the Charger was a big muscle car, so we asked ourselves ‘How do we make it the fastest muscle car ever?' This car has a split personality. It gets 22 miles per gallon on the highway and does a 10.8-second quarter-mile.

"The team overcame every obstacle and the car became the best version of itself."

More than a year after Hellcat sales began, Cowland remains proud that the engine can run flat out for protracted periods. Some automakers protect their engines with software that reduces output after 10 to 30 seconds at max power. "Our requirement is 20 minutes of track time at full rated output," Cowland said. "You can make drag strip run after drag strip run with no deterioration in performance."

The Hellcat Charger sedan has a top speed of 204 mph, the Challenger 199.

"We built it because we could," Cowland said. "We wanted to make a statement and move the brand forward.