It’s a rare perfect day in Chicago, where the weather typically boils down to Snow Removal and a few weeks of Road Construction Season. Warm but not too hot, the humidity and mosquito situation are remarkably peachy as well. Driving along in your ride, you feel like you’d be ticketed for not taking advantage of this rare climate event, and you hit the DOWN button on your driver’s window.
BOOMBOOMBOOMBOOM. Ouch! It’s like a jet taking off. If your kid rolls down a back window alone it’s even worse- seems like your eardrums will rupture. Opening the sunroof adds more unpleasantness. In the twelve years I owned my previous car, I think I can count on the fingers of both hands the number of times that I had the giant glass roof open; if just wasn’t pleasant to drive. Is this just my car, or are others experiencing this?
Mass Collisions
Apparently, I’m not alone, and there’s a reason for this phenomenon. I did some quick searches for ‘Buffeting’ and ‘Buffett’, and after dismissing the many links dealing with a Boomer musician that performs to thousands of aging Tommy Bahama clad fans, I found some answers.
According to a number of sources, including The Family Handyman of all things:
The throbbing, helicopter-like sound is the outside air passing over and interacting with the contained air inside the vehicle.
When the two air masses collide, they compress and decompress repeatedly. This produces the throbbing effect. It can be as loud as a commercial aircraft.
He continues:
Many variables contribute to the effect: car shape and size, how far you lower windows down and your speed. The effect can happen when any single window is down, including the sunroof.
The helicopter sound is more pronounced when a rear window is down. This is because the side mirrors are designed to direct air flow away from the front windows. Lowering a rear window amplifies the effect.
So you aren’t imagining that the rear windows lowered alone always seems far worse. But why? More importantly, why can you roll down the side windows in a ’67 Impala and not experience this phenomenon so badly?
Good Aero Is Bad?
Well, good aero is certainly bad for windows down driving. Today almost all cars are very aerodynamically efficient, the air clinging tightly to the outside of the car.
As The Family Handyman says:
When a window opens, the air flow is disrupted, magnifying the buffeting effect. Older vehicles were designed less efficiently, and air leaked from their insides. The leaking air relieves the pressure caused by wind buffeting, reducing the effect.
Obviously, the one solution is to open another window, but that still doesn’t eliminate the problem, just reduces it. Is there a solution? Historically, there have been a few, and some from very unlikely sources.
[Editor’s Note: I actually wrote about this ten years ago (holy crap) and I asked an actual physicist, not some internet handyman. Here’s how Dr. Stephen Granade explained it to me:
That “whum whum WHUM WHUM” noise happens because the wind passing over the small window opening is like a bored drunk blowing over the neck of an empty beer bottle.
Air passing over an opening forms tiny tornadoes as it moves past the front edge of that opening. When those tornadoes, or vortices, reach the opening’s back edge, they make a wave of pressure that pushes air into and out of the car. Since sound is nothing more than waves of pressure, this makes noise. If you’re driving slowly the effect’s not too bad, but if you drive fast enough, you reach a resonant point. Imagine I stand by your open car window and use my science powers to push on the air inside the car, compressing it a bit. The car air then springs back out, then back in, then back out, then back in. With each cycle of moving out and in, the amount of air movement gets smaller until it completely dies away. But if I push on the car air again just as it finishes springing back out and is headed back in, and I do that over and over again, the amount of air movement gets a whole lot bigger and doesn’t die away. That’s what happens when you drive fast enough. The vortices keep pressing on the air in your car just at the right time to make big pressure waves that we can feel and hear.
The technical term for this effect is the Helmholtz resonance, though car people call it “side window buffeting”. Back in the 1850s, a scientist named Hermann von Helmholtz showed that the sound’s pitch depends on the size of your container of air and of the opening. The bigger the container of air, the lower the pitch. The smaller the opening, the higher the pitch. If you blow over a bottle, you get a medium-pitch whistle. Since a car’s a big container of air, you get a low throbbing noise.
So, there you go, from an actual, working physicist! – JT]
Cracks In History
If you’ve opened a sliding rear window in a pickup you know how that really helps airflow. Instead of the truck cab being a pressurized box or a big air scoop the wind has a place to escape. Even some cars had an answer for this, particularly Mercury cars from the sixties with power lowering rear backlights:
Mercury supposedly dropped the feature after air conditioning became popular, but if you’ve ever owned a black-on-black car you’d kill to be able to get the hot air flushed out of your ride this quickly and help the poor climate control do its job.
Another great solution came from what might be the oddest place imaginable: the designers and coachbuilders at the Italian firm Zagato., often makers of some of some of the most bizarre automotive creations ever (even by Italian standards). Maybe they discovered this by accident and made it a feature, but the hatchbacks of a number of their cars could be electrically raised by a switch on the dashboard. Here’s the feature on an Alfa Romeo Junior Zagato:
Or on this Lancia Fulvia Zagato. By the way, you could still open and close the hatch when is was raised since the latch itself moved:
If you scroll forward to the 15:00 point in the video below you can see it open. Like the later Stratos these Lancias make noise that hits the receptors in your brain in such a way that you want to triple the speed limit and not care about the consequences.
This Lancia Flavia Zagato might have been the first one to have the feature back in 1962.
Shit, look at that thing: if aliens really landed in Roswell and instead of being probed and killed they were put into slavery designing cars, you might imagine their creations looking something like this. Why do I want one so much?
Needless to say, I have heard that owners of these cars will get people at stoplights yelling at them YER HATCH IS OPEN BUD! Which is understandable.
The Matra Djet had a far less sophisticated way to deal with the airflow issue, almost out of necessity if you believe the remarks at around 4:30 by this somewhat familiar reviewer:
I’ve found that T-tops and targa roof cars are particularly bad in the buffeting department, except for cars like the Honda CR-X Del Sol or the Miata RF where you can roll down the rear backlight. Only one Nissan Z car I found to be reasonable with the roof panels off, and that was the disco-era 280ZX 2+2; it had remote control rear quarter windows to let out the pressure.
Our family had a later 1990 Z32 which had no such openings and was essentially undriveable at speed with the roof panels removed.
Banishing The Boom
The aftermarket has actually latched onto this idea, literally. There are numerous sources that offer a clip that Corvette owners can put onto their hatch to allow the thing to close and secure but leave a few inches of air gap to relieve the pressure of the big targa air scoop (at least on C4s).
I found a bunch of suppliers making these things so they MUST work, right? Why can’t mainstream OEM manufacturers latch onto this idea?
Once again, I’m using the Tesla Model 3 as the guinea pig of this device. Right on the switch panel for the windows would be a button to pop the glass on the hatch just enough to get air flow to run through. Of course, being a Tesla they’d probably make you go through a bunch of menus to open this thing, but let’s just apply logic anyway.
One detail- you might need to add a small mesh screen that raises with the window. My fear is the the airflow will be so good that your gas receipts and wedding invitations or whatever is on your seats might end up the street behind you without it.
Look, we all want fresh air now and then, but we want our eardrums not to bleed in the process. Do we need to buy a car with the aerodynamics of a brick to get that? I don’t think so, especially if there’s a trick we could employ to give us the best of both worlds.
The Tiny Rear Wipers On Modern Cars Are Pathetic But I Have A Solution – The Autopian
Third Brake Lights Should Be Mounted On Rear Wiper Arms – The Autopian
This Could Be A Fix For The Stupid Little Arcs So Many Rear Window Wipers Make – The Autopian
I also wondered why the modern moon roofs have a screen that pop up. I find them ugly, and they block 20% or so of my view outside as a driver. I figured it was the fact that the front edge of the moon roof is lower than the rear edge, where my 1993 Taurus had a flat roof and had no problem without a screen. Perhaps the angle of the windshield combined with the flat roof solved this issue.
the screen the pops up on the leading edge of the opening appears to make it quieter. I can hold it down in my car so it won’t pop up and the difference in noise is noticeable.
Yeah, I figured that out. I just didn’t write that into my comment very well. It’s an odd game to pull down the screen, then let it pop up to feel the difference in the booming effect.
THANK YOU for writing this article!
We discovered that our 1993 Taurus SHO and 1999 Prius had perfect airflow when two windows were open on the same side. You’d feel the fresh air flowing around your head, and yet there was little buffeting and it could be quite quiet if you opened the windows away from other traffic.
A 2013 hatchback would produce the buffeting when I tried it. I figured hatchbacks were the problem, but a newer Malibu also has buffeting. Now I know. Are windows-down a thing of the past?
Yes and no, they want you to use the AC as it is more efficient at higher speeds—though in my experience even with multiple cars with respectable aero, the difference is negligible, then again, I probably drive slower with them down—but it’s more a byproduct of efficiency than intent.
I just prefer the air from outside over the air conditioning. I remember my ’83 Lynx with the slots in the hood had fresh air the same temp as the outside air. My ’89 Taurus brought in the vent air from under the hood, and it was a few degrees warmer than the outside air. I did not like that, even though the ’89 SHO was superior to the Lynx GS in every other way!
I can report that a 2000-2005 GM H-body (LeSabre or Bonneville) has no such issues. Whichever windows are open, no matter how far, at any speed, NO BUFFETTING EVER.
Didn’t certain Tesla’s already have a built-in vent? You just had to retrieve your top from the side of the highway when you wanted to put it back on.
Interesting. I have no issues with my Grand Cherokee if I open the 2 same side windows or all 4, which allows air to flow thru, but if I open both back windows it feels like my eardrums will burst. So I don’t do that.
Buy a 4Runner. Just roll down the rear window. On a nice sunny day, having the sunroof open with that back window and the front windows rolled down is the best. Just make sure you close that rear window before you head off road. I made that mistake once, and I’ll never get all the dust out of the interior.
Yes! This is the answer. The answer is always 4Runner. Some people say Miata, but they are factually incorrect.
Can confirm both scenarios! Pro Tip: Use the window lock switch in order to prevent unknowing passengers from rolling down the rear window in dusty environments… 😮
After owning eight P2 v70’s and having family members who are very sensitive to the Helmholtz eardrum assault, I can conclusively state with peer-reviewed scientific certainty that after the A/C compressor inevitably retires somewhere b/w 200 and 250k, lowering the same side rear window nearly the exact same distance as the front (exact window drop length is a less important factor here) eliminates this buffeting, and allows for a desirable car-wide circular interior airflow (ie: clockwise when observed in plan view if right side windows are cracked open). If you lower the opposite side rear window, this may reduce the buffeting, but this nice breeze is disrupted, and is slightly louder in these wagons for reasons
i dont care abouti have not explored.In addition, if the passenger side windows are the ones being equally lowered a bit, i can still hear conversations/tunes/traffic better too, while getting a better cooling breeze for the driver than if the driver’s side windows are equally lowered (less-good counterclockwise airflow for the driver).
I dream of adding two window mods to these cars:
-rear cargo area side windows that open like a dodge caravan’s rear side windows. Hinges, latches, and mounting holes in the window are easy, but i dont know how to make the seals work with vertically hinged windows in this car. Quite custom i imagine.
-rear liftgate window being able to open, like in some older bmw wagons (also likely a significant challenge, but maybe less so with the horizontal hinge axis? i dunno).
These improvements (coupled with repairing the A/C compressor, naturally) should elevate this wagon’s status to that of Most Supreme Family Hauler ever, if it didn’t have that distinction already.
This Nissan Wagon Has The Best, Least Appreciated Wagon Feature (jalopnik.com)
Jason wrote about how a certain Nissan wagon had a roll down THIRD row window
I believe the technical terms are “deosil” and “widdershins”. 🙂
E46 3-series BMWs (coupes, anyway) have rear windows that pop out a bit at the back. Power, even. I think this is similar to what’s refered to in the first comment (EF Civic). Anyway, works to eliminate the drumming
I think another think affecting this effect is how tight cars are these days. With all the windows up some of my cars resist the door closing properly, the air being forced into the car by closing the door has no where to go. The “standing wave” as I called it, doesn’t happen in my Subarus though, actually not that surprising. I once has a Kia Optima rental that was so bad the parcel shelf was “flapping” about an inch or so. I’ve usually found just cracking a rear window “fixes” it though.
Black_Peter- the tightness is indeed a factor. I wondered why our old VW wagons (type 3 and 4) didn’t have ear-drum-breaking disturbance (despite being famously air tight/capable-of-floating cars as well as having fixed rear quarter windows) but they DID have those big cabin exhaust vents on the pillars in back (still a terrible car to spend a Southern summer in, let me tell you).
That’s a door seal design issue, like on VW Bugs. On Bugs, the door starts sealing at the hinge side as soon as you start closing the door and continues to seal along the top and bottom of the door as it is being closed. The door is, as you say, forcing air into the car by the door and its seals in as it is being closed.
Most modern cars, like your Subarus, don’t have that issue because the seal doesn’t come into contact with the body until the door is closed. Air can escape up, down, left, and right as the door is being closed until the very end.
“Modern cars like your Subarus” That’s so cute you think Subarus are “modern”.. I prefer “only just non-agricultural”.
This isn’t Subaru exclusive, but the BRZ/GR86 frameless windows automatically crack up a little when the door opens to avoid the pressure on the glass when the door is shut again, whereupon the glass automatically closes all the way.
Good way to create a tight seal on the gasket without stressing it every time you open/close the doors too.
I have a ’67 Buick Skylark and it is an absolute pleasure to drive at any speed with the all of the windows rolled down or just the driver’s window down.
BTW, the Malibu in the illustration is a ’65.
By the way, I’ve noticed this wind-hits-you-in-the-side-of-the-head buffeting problem in every sedan I’ve ever driven. I always solve it by lowering the rear window.
But for the record, I’ve never come across this in a coupe, I presume because of the longer doors / windows.
Coupes are the answer. Also pop ups rule. Get off my lawn.
Yeah, I didn’t get it in my coupe because I assume it was buffetting the headrest or just behind it. The b-pillar on my Volt is so far forward that buffetting hits me in the head (and also makes it uncomfortable to have my arm up on the sill, boo). But at least, with the sedan, I have a rear window to crack, just enough to relieve the pressure as you said.
Look up any review of the new Supra, they all say it is unbearably bad in them. I agree most coupes are not like this though.
Good mirror design on your coupe?
Maybe, but it’s probably not a relevant example since my coupes are both Firebirds, a 2nd- and 3rd-generation, and the mirrors are laughably small compared to today’s typical ones.
My ’10 Focus seems to have what I think is an ingenious little effort to help combat this a little from the outside.
Both of the wing mirrors have 3 little shark teeth edges (like the rally car thing that we mostly associate with Autozoned-out Civics, just more tasteful) along their top edges to help smooth airflow up and over them.
Could be for aero, but I recall reading it’s to help with the buffeting.
Pressure relief valves? Cracking the back hatch to allow air flow? We’re talking about car farts, right?
Had a shitty ’97 S10 for many years. Like most other single cab pickups, if you roll down the driver’s side window, the air rushing in hits you right in the side of the head, and it’s super annoying. Rolling the other window down too didn’t make any difference. One day this shitty S10 decided to drop the driver’s mirror completely off. And what I discovered, completely by accident, is that an S10 with no mirror no longer has this buffeting problem.
I’m not suggesting to go bust off your driver’s side mirror, but I’m also not not suggesting it.
I just posted about my Ford sedan’s attempt to deal with this and still retain the mirrors! It really does seem to work, compared with older stuff.
Another approach is to have a permanent set of vents in the back, as with the “elephant ears” on the C-pillars of the SAAB 96:
https://4.bp.blogspot.com/-Ixx2E5s0fRY/Um-sb-BJazI/AAAAAAAAbqY/BLPTs-iEf9c/s1600/img010+(2).jpg
or the more straightforwardly vent-looking vents on the flanks of the 99:
https://saabworld.net/wp/wp-content/uploads/2016/08/Saab_99_brochure_1975_USA_12.jpg
My ’78 2 door Corolla has both pop out rear windows and those vents in the rear fenders that allow air to exit the cabin and prevent buffeting. It’s funny how with better HVAC systems and the need to seal up the car’s interiors even further, we’ve created this new issue.
Well shit! Now am feeling compelled to tell the story of how Mr. B. came to spend the night at my apt. in 1977. (stops and does some simple math) Apparently the statute of limitations has not yet expired regarding some of the alleged activities that occurred.
That’s ok though.
As a fan, I’m listening.
This problem makes me bonkers, especially when a kid puts down a rear window at speed. By the time I register it and I get my hands on the controls I have to endure a good 5 or 10 seconds of total ear drum brutality before I find the window switch and get their window up or mine down.
Seems it would be a simple enough software fix for the car to recognize any window going down (or already being down) when the car is above a certain speed, and just automatically open the diagonal window an inch or two to compensate.
This is completely relatable. I’ve repeatedly had the same thing happen. My kids are old enough now they have learned to ask to roll down the windows so I can roll mine down with them.
>…” they have learned to ask to roll down the windows…”
did your training regimen involve just repeatedly yelling at them until they learned? asking for a friend.
Or maybe ‘dope slaps’ á la CarTalk?
You don’t have power window locks?
I don’t remember a buffeting problem in my Z31 300ZX t-top.
JumboG- the S30 2+2 we had before the Z32 was fine with windows down, but it had manual flip out rear quarters AND very cool cabin exhaust vents disguised as round Z logos on the C pillar.
Yeah, the vented badge was a clever implementation of early flow through ventilation. Aero on those cars was also horrendous, so that probably reduced the problem. I seem to remember buffeting happening in my 2-seaters, but it would have been nothing like you can get in modern cars.
But what all new cars really need is wing windows.
Fuckin-A screen doors on a Tesla, I’m in!
Do people not know to crack the back opposing side window to combat buffeting?
what about the pressure relief vents hidden in the trunk under the bumper that just about every car seems to have nowadays? I have seen bumperless cars and when they move the vents open, when they stop they close?
That’s part of the flow through ventilation system. It’s a passive pressure relief that mainly works when the car is moving. They’re located where low pressure airflow allows the flaps to open, pulling the air through the car, and increasing HVAC efficiency. It also works a little when stopped if internal pressure exceeds external pressure enough.
I remember reading a previous DT or JT article that cars have a one way vent when you close the door to relieve the pressure inside. couldn’t this same vent/valve be opened when the windows go down?
live2ski- all cars do have that mandated one-way vent, usually under the bumper on most modern cars (last one I can think of that had an exposed one was the 2007 100 Series Land Cruiser that a friend has). However, this vent (which is technically always ‘open’) is no match for windows down at speed.
No, they’re passive flaps. They relieve pressure waves from door closings or static higher interior pressure differential, but mainly they’re there to help the efficiency of the HVAC system by allowing air to flow through the car more effectively so that the HVAC fans aren’t working against a higher internal pressure. Outside air comes into the car from a vent located in a aerodynamically high pressure zone—often the base of the windshield—and flows out through the passive flaps at the rear located in an aerodynamically low pressure zone. To some extent, they would do as you suggest on their own, but the effect is too small and too far from the occupants to make much difference.
The ’71 Plymouth Duster my family had when I was a kid had quarter windows that – despite the car having no sunroof – would open slightly via folding latch. You can kind of see the latch in this picture: https://i.ebayimg.com/images/g/FK8AAOSw5Tpaqbl0/s-l1200.webp
That car also had “crotch coolers”, which were simply passive vents in the front footwells that had little doors on them. Open the door, allow fresh air in to deswampify one’s arse. Beware, however, if the door hadn’t been opened in a while: the initial pass-through of air would blow out the dust, etc. that had accumulated in the vent. Fun.
Mine did the same thing. And the little vent boxes were a great place to hide your stash.
Solution is to roll down one window in front, and crack the one on the rear, opposite side. Works great.
Also, reason #57193 why EF civics are one of the best cars ever; the pop out rear glass is amazing. With the windows down and those open, I don’t even really need air conditioning.
If I want air movement but not a solid facial wind buffeting, I’ve had great results with both passenger side windows being down