The muscle car that has more than 700 horsepower

When it announced plans for the new 2015 Dodge Challenger SRT Hellcat in May, Chrysler's performance brand said it would deliver "600-plus" horsepower.

It turns out that was a big plus sign.

The 2015 Dodge Challenger SRT Hellcat
Chrysler Group LLC | PRNewsFoto
The 2015 Dodge Challenger SRT Hellcat

Earlier this month, the brand revealed what it is calling "the most powerful muscle car ever," coming in at a screeching 707 horsepower.

Buyers will be given two different key fobs to start the 6.2-liter engine. The red one, Dodge said in a release, will "unlock the full 707 horsepower and torque potential of the Challenger SRT Hellcat engine. The black fob "limits the driver to a reduced engine output of 500 horsepower."

The introduction of the Challenger SRT Hellcat marks the first use of V-8 supercharger technology for Dodge and SRT. A full 91 percent of the engine's content has been revised, said Chrysler's Powertrain Director Chris Cowland.

The car also comes with a new Drive Mode system, which offers more than 125 different settings on features such as steering assist levels.

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The vehicle's supped-up horsepower suggests it will blow right by the new Corvette Z06, which is rated at 650 horsepower. Still, the race is likely to be closer than it appears at face value, as the 'Vette will be significantly lighter than the Dodge. Meanwhile, that other mean machine from Dodge, the Viper, puts out 640 horsepower.

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Chrysler is looking for a way to kick start Challenger's sales, which are trailing those of the Ford Mustang and Chevy Camaro. Its June sales fell 14 percent compared to the prior year and are down 12 percent so far this year.

The 2015 Dodge Challenger SRT Hellcat will arrive in dealerships during the third quarter. Pricing will follow in the coming weeks, Dodge said.

By CNBC Contributor Paul A. Eisenstein. Follow him on Twitter @DetroitBureau or at