Why Does the Ford Mustang’s Door Sound Like It Vacuum-Seals?

Red 2020 Ford Mustang EcoBoost Premium front angle view 2020 Ford Mustang | photo by Patrick Masterson

You might think the 2020 Ford Mustang EcoBoost Premium would be an easy car to write about, but we’ve covered the Mustang extensively — from the EcoBoost High Performance Package to its manual transmission as an industry exception to the fire-breathing Shelby GT500. As I took a lap around the outside of one recently, I gave it some thought, got inside and shut the door. That’s when I heard the curious sealing sound of what Ford calls Short Drop Glass.

Related: 2020 Ford Mustang EcoBoost High Performance Package: 6 Things We Like, 3 Things We Don’t

For a demonstration of the subtle, vacuum-like noise, here it is in action:

The Short Drop Glass function isn’t unique to the Mustang (though it is unique to the Mustang in Ford’s lineup) and or even all that new of a feature, but what does it do? According to Ford spokesperson Berj Alexanian, Short Drop Glass “lowers the glass when either door is opened to improve door efforts and sealing. The glass returns to its closed position when the door is closed. The seal is part of the car frame — not the door — so the glass window does a short drop to clear the seal.”

In other words, Short Drop Glass can help with things like climate control and wind and road noise due to the sealing, but it also helps preserve the actual glass of the window because it reduces the contact the window has with the car’s frame.

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Don’t be alarmed by this sound if you aren’t familiar with it. In fact, you may want to be alarmed if you don’t hear this sound when you open either side door: Short Drop Glass was introduced for the 2005 model year and is now standard on all Mustangs, so if your windows aren’t making that little vacuum noise when you open and close your doors, you may need to take it in for a repair.

There may be more obvious features on your 2020 Ford Mustang to look after and maintain — in my case, it was the conspicuous Rapid Red paint job with white racing stripes, high-gloss black 18-inch aluminum wheels, six-speed manual transmission and leather-trimmed power adjustable seats. But the small sound of a properly working window seal can ensure your ride in a new Mustang is just that little bit smoother.

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Photo of Patrick Masterson
Patrick Masterson is Chief Copy Editor at He joined the automotive industry in 2016 as a lifelong car enthusiast and has achieved the rare feat of applying his journalism and media arts degrees as a writer, fact-checker, proofreader and editor his entire professional career. He lives by an in-house version of the AP stylebook and knows where semicolons can go. Email Patrick Masterson

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