I own a '17 Equinox with wind buffeting noise. In addition, the whole vehicle will shake and vibrate. It is staying at the dealer for a dashboard electrical problem ( 5 time back ) also so I have an '18 Equinox loaner to compare. There is a difference between my '17 and the '18. It is absolutey HORRENDOUS> The vehicle vibrates un controllibly, the driver door panel vibrates violently and forget using the mirrors.. They are of no use. This is absolutely the worst , and I mean the WORST excuse for a modern day vehicle. I worked for Chevrolet Motor Division for 38 years in various service related positions. I got a hew company car every 3,000 miles ( every 6 weeks. This is absolutely the worst piece of crap I have ever driven. What a **** poor exercise of vehicle design and they think this is acceptable because they state in the owners manual that this is "normal". You don't get the owners manual until after you purchase the vehicle. I have $50 cold green cash for anyone can drive this Equinox for 1/2 half hour at 70 MPH. This is pure unadulterated horse manure to have to put up with this.

 

When does the buffeting noise occur? All the time? Does it vary with speed? Are the windows up or down?

If the noise you are describing is being caused by wind/air when one or more windows are open, then it actually is normal and it's known as the Helmholtz Resonance. This article from Car and Driver does a good job of discussing what exactly it is and why it occurs. Unfortunately, most modern vehicles and more prone to it because they are more aerodynamic and their cabins are sealed better. There's nothing anyone can do to resolve this issue without extensive modification to the vehicle's exterior to alter it's aerodynamic properties.

Our 2007 Equinox buffets terribly if you roll all the windows down at highway speeds.