I absolutely love the Toyota 4Runner. It’s an old-school SUV filled with character, charm, and personality. I own a 2010 model; it was the very first car that I bought during my junior year of high school, with 110,000 miles on its odometer. I am now almost a junior in college, and the car is quickly approaching 170,000 miles. I’ve daily driven it up and down the East coast and everywhere on Long Island. It needed nothing except oil changes, tires, and gas. Lots and lots of gas. One of the reasons why I chose to buy a 4Runner for my first car, besides planning to own it for a long time, was the adventure-aspect associated with it. Between 4WD, the interior simplicity, and plenty of space, it’s my go-to surf/bike/kayak/ski/scream Vampire Weekend-at-the-top-of-my-lungs rig. It also has one feature that I absolutely worship: the roll-down rear window. I’m sure you all know about this feature, but I’m here to point out one of its major flaws.
I constantly roll down the rear window throughout the year, typically when temperatures reach 45 degrees or above. The breeze is just unmatched. Who needs a Jeep Wrangler when you can roll down all four windows, the sunroof, and the rear window in your 4Runner? Not I! (Plus the 4Runner has an awesome button for “party mode,” which essentially just reverts the audio to the back tailgate speakers. Checkmate, Jeepers. Sorry, DT).
However, as much as I love hanging my head out the back window after setting the cruise control on and praying my truck is aligned, so does my furry friend (heads up, I do not actually do that, and I strongly recommend that you do not, for obvious reasons). He’s a little pup. He can hardly see out the windows while sitting in the front, let alone the back. I’ve let him sniff around there in the past; it has brought a lot of wallpaper-esque photos. But he’s much too small to comfortably enjoy the open-air experience. Other dogs, yes, but sadly not him.
Yet, there’s one tragic flaw with allowing your pup to stick his big slobbery tongue out the back window of your 4Runner: exhaust fumes. You see, the exhaust pipe on the 4Runner is placed below the bumper, rear facing, like many other cars. No problem, right? Not quite. Once you open the rear window, the pressure from traveling at high speeds seems to create a “vacuum effect” of pressurized air, sucking fumes into the cabin. The nearly vertical tailgate of the 4Runner only contributes to this as well.
Typically, when a car has an exhaust leak of some sort or another, I believe it’s fairly common to smell a “rotten egg/sulfur” smell when driving [Editor’s Note: Sometimes you might smell exhaust gases, but oftentimes it’ll seem completely odorless. I know this as someone who’s had to deal with countless exhaust leaks. I carry a carbon monoxide alarm in all of my older cars. -DT]. However, we late model 4Runner owners experience this awful smell when accelerating with the rear window down, with no apparent leaks. On Trail4R.com, a 5th generation 4Runner owners page, Brenan Greene writes:
The vacuum whirlwind of gasses behind the 4Runner is following us down the road. As this vacuum effect starts pulling the gasses up and behind the 4Runner, we often smell the rotten egg fumes through the open rear hatch window.
Whether you notice the smell or not, the reality is that driving with that window down is a risk — one that Toyota itself acknowledges in its owner’s manual:
That’s the 2010 manual above; even 2023 4Runners include essentially the same warning in their manuals:
[Editor’s Note: This is fairly standard in the industry. Jeeps have the same warning. Here’s a warning about the 2008 Jeep Grand Cherokee’s rear “flipper glass”:
My 1994 Jeep Grand Cherokee features a similar manufacturer’s warning about driving with the rear glass open. -DT]
How does one fix this issue?
Well, what could help is rerouting your exhaust to the side. With a side exit exhaust, you could remove some of that vacuum effect created by the factory exhaust location. Side-exit exhaust could force the fumes out and away from the 4Runner, letting the wind take it down the road, and ultimately out of your cabin.
It’s not a cheap job, but it could get rid of exhaust smells and improve safety for yourself and your furry passengers, though this is not an official recommendation; the official recommendation is to follow Toyota’s advice in the owner’s manual.
This brings me to my next point. Why didn’t Toyota engineer a side-mounted exhaust for the 4Runner? The Tacoma has one, and it’s built on the same platform as the 4Runner. I cannot imagine it to be too costly for Toyota to engineer this, considering the current generation 4Runner has been on sale since 2010.
It cannot be good for Fido’s lungs as he sticks his head out the window of his owner’s 4Runner as they cruise together down the PCH. Hopefully owners like myself take caution, monitor window usage with their pets, or even modify their exhaust and possibly carry a CO alarm onboard.
In any case, I just wanted to share with you that one bit of caution about a 4Runner feature that, let’s be honest, everyone thinks is just cool. And it is! But just understand the risks and limitations.
Images: Author, Toyota, Jeep (owner’s manual)
I have a 2021 4Runner TRD Pro with the factory side mounted exhaust and I still smell fumes coming into the car while accelerating when the window is up or down! It smells like rotten eggs.
“Why didn’t Toyota engineer a side-mounted exhaust for the 4Runner? The Tacoma has one, and it’s built on the same platform as the 4Runner.”
Just being pedantic here – but if you can’t be pedantic about cars on the Autopian, where can you be? – the 4Runner and Tacoma are not built on the same platform. They were in early generations, until (IIRC) 1995. The current 4Runner is related to the Land Cruiser Prado, and the Tacoma uses a Tacoma-specific frame and platform. Their frames, engines, transmissions, and many other things are not shared. It’s odd that they aren’t more closely related.
They’ll allegedly share a platform again in their next generations, as Toyota moves body-on-frame vehicles to TNGA-F. The Sequoia, Tundra, and Land Cruiser are already sharing parts with their latest generations.
My dad had a ’92, and in those ones, the only way to open the rear tailgate was to roll down the window… well that’s great until the window motor packs up with the window down. Oh did I mention we were towing a boat. Oh and it was a 2.4 Turbo Diesel. It was horrendous!
I had a ’91 GMC Suburban that suffered from this issue or boasted this feature, however you want to look at it. I figured it allowed me to experience what all the cars around me got to experience, it was a pretty stinky old truck!
I have never noticed this in my 2012, possibly because the main reason I dropped all the windows was to smoke, so I was supplying my own noxious gasses. Maybe now that I’ve quite I’ll see if I detect any odors.
For those who are still smokers, dropping the back window is awesome! It eliminates the buffeting typical of lowering only the side window and creates great airflow so the cig smoke doesn’t linger and stink up your interior. Toyota will never advertise this but it’s the perfect SUV for smoking!
1987 Grand Wagoneer owner here. Plenty of people have approached me to share their own stories of why they’d drive a Waggy with the rear window down (most involving cannabis), but nearly everyone has mentioned the same vacuum effect sucking toxic, smelly exhaust back into the car. Jeep sort of (and I mean barely) solves this with a rear spoiler that my car has. It sort of screws up the lines of the car in my opinion, but it does mean I can drive at highway speed with the rear window down. I’ll roll down a couple of windows up front to help keep things fresh. Of course, the issue comes right back when you stop at a traffic light. So close.
Thanks for sharing! I love the Wags, I’ve been searching for a decently cheap one in the Northeast that isn’t rusted to turds. Combine that with my 4Runner, I’ll conquer the roll down rear window market.
I’ve got an 86 4Runner and my exhaust is routed to the side. You still can’t drive with the rear window down.
Yep this is true. My 2021 $runner TRD pro has the side mount exhaust and you still get the smell. I even get it if my rear window is up if I accelerate hard enough.
I did not even think of this. My mind went right to rust and electrical failures.
of just the rear window going up and down not the entire 4runner, just the rear window.
Can anyone comment on the opening rear window on Tundras? I believe the first generation crew cab had a retractable window, and over 5′ of cargo box between the window and tailpipe.
My truck has a sliding rear window but I only use it when hooking up trailers, the rest of the time I use the flip out side windows in the extended cab.
I have a 1997 4Runner. Check the rear spoiler on that generation – the shape of it makes a big difference, because it pulls air off the roof down into the suction zone behind the vehicle. I noticed they changed the shape of the spoiler in later generation 4Runners so It no longer does that.
As many others have said, this was also a “feature” of station wagons. I owned a couple of 4Runners, so have come across it there too.
Islip and Sunrise Toyota – all part of my old stomping grounds growing up, back when Sunrise Toyota billed themselves as the “wonderland of import cars,” and my German-learned-English-in-Brooklyn grandmother would call them toy-OTTERS.
A fellow Islander! Sunrise Toyota is great; I bought my truck from them and get OEM parts from them as well. It’s worth the 45 minute drive.
I grew up by Patchogue, back when Sunrise had traffic lights everywhere.
We still have them over here in Nassau County…
We had a 2000 4Runner, and with the back window down any amount exhaust would get sucked into the vehicle. Even with the exhaust pipe on the side.
As Plesiomorphus primitivus said that generation had the option of a rear spoiler similar to what station wagons had. My parents had a ’78 Caprice Classic wagon w/ that spoiler arrangement and you could drive w/ the rear window open w/o getting exhaust in the car.
I can’t speak to what the 4Runner experience is like as I’ve only briefly ridden in them but I can say with the utmost certainly that that pooch is a good boy.
He is!
The station wagon has been gone longer than I realized.
Long enough that I have never rode in one! I’m 20, ouch.
The real solution is to ditch a lift gate and go split gate as God intended.
Split gate like the previous generations LC and LX is the answer. Not the abomination of the swing gate that the gx has.
The swing gate on the GX is horrid. It would be fine if you lived in a RHD market, not over here in the U.S. It’s especially horrid living in NYC which is why I chose a 4Runner and not a GX.
I’m just commenting to ask about the edit, notifications etc… that were teased in the email a week or two ago! Bring them to us already!!!!
Also, my wifes Kia Telluride blasts the tailpipe DIRECTLY into backseat where I need to load my children unless theres wind to blow it away. It drives me insane and honestly is a big reason we will never buy one again. It’s silly, but it never happened with our 4runner or my Tundra..or my tacoma or my moms caddy….you get the point. Oh and you can’t lift the wipers to remove snow and it squeals at startup. Okay now I’ve listed all its issues and fully went on a tangent.
Wait… you can’t lift the wipers?!
No, you have to wait for it to unfreeze, you can’t have them pre-lifted or lift them to clear after a storm. It was NOT made for winter. I just loaded my daughter with the exhaust going in her door again I am starting to hate the car and so is my wife, we won’t ever buy kia/hyundai again. had a really bad experience with there warranty stuff too.
If it’s anything like my ’16 Optima, the wipers are “housed” below the rear-most part of the hood, and you cannot directly lift them off the glass without thinking ahead.
If the weather ever called for me wanting to lift the wiper blades when I parked, I’d have to remember to – within 30 seconds of shutting off the ignition – hold the wiper stalk in the “Mist” position for 5 seconds. This put the wiper arms into their “service” position. They would then lift and stay off the window.
My new ’22 Mazda has a very similar way of doing things, so this is probably going to become more common in the industry as a way of “hiding” the wipers from the wind, in chase of that 0.01% advantage in aero.
FWIW, even if I didn’t raise the wipers when it snowed, it really wasn’t a big deal to get the windshield clean enough that a couple swipes of the wipers couldn’t clear the rest.
I ran into this problem on my wife’s 2016 4runner, a harbor freight exhaust cutter did a good job of making space for a 90 degree elbow to keep my great dane’s two brain cells functional. Too bad it went through two transmissions in three years because we towed a camp trailer 2000 lbs under the weight rating with it a few times. Loved the rig but need to tow on occasion so it had to go. You have no idea how disappointed we were to have those failures, and yes the dealer installed the new transmissions so I assumed they were done correctly with new parts.
Was that covered under warranty?
Wrangler owner here: Have been dealing with this for years. Best way to combat is 3/4 angle away, and turn down exhaust tip. I tried a 90 degree, still got fumes, then adjusted to 45 degree, and did a turn-down at the advice of the exhaust shop. Never had a problem again. A fully functioning catalytic converter, freshly tuned engine helps as well.
On my 2008 4Runner, I cut off the resonator and tail pipe and put a 90-degree elbow on it to make the exhaust exit just behing the right rear wheel.
Guess what?
No more exhaust fumes in the truck when cruising with the rear window down.
Tools needed? Hacksaw, wrench.
Parts needed? 90-degree exhaust elbow and exhaust clamp from the parts store, exhaust tip if feeling fancy.
Time required? 30 minutes if actually using a hacksaw, 10 if using a reciprocating saw instead.
Thanks for the content idea… I’ll throw you a penny.
Didn’t work on my CJ, when I bought it the exhaust dumped in under the drivers seat, so I angled it 90 degrees to exit in front of the rear axle and the topless brick sucked it back in. Doors and having a longer vehicle might make the difference.
Late reply, but my ’74 has it straight out the back and it still sucks it in. Doors on but all windows open. I cut a home depot 90 in half and have it turned down like /—-\ from the back and out. Better but still stanky
Wow, three good pieces in a single day – Rob, you’re clearly off to a fantastic start!
I have to wonder though if your truly Autopian colors are going to show when you try to keep up the pace when the crazy of college rears its head…you’ll be all addled and bleary eyed, turning out oddly typed rants at 3am about gas station video ads at the pumps or something (“damnit I don’t have a pen when I’m filling up how the hell am I supposed to remember this recipe for easy party pastries am I right?!”)
Thank you, Jack! Who says I’m not getting there already??
I never thought of this. I had a 2021 Lexus GX 460 at one point. While that car doesn’t have a roll-down rear window, it does have glass that lifts separately and that can theoretically be left open while driving.
Until you hit a bump, sending the glass slamming shut evidentially ending your drive covered in glass shards. Dont do this please.
^^ Avoid doing that. I was on Nantucket Island once, saw a Range Rover Classic driving with the hatch glass up. Next thing you know there was a bump and glass all over the road. Save yourself!
I deal with this in my Scout. Even with a side exhaust the fumes sneaking back into the cabin with certain window configurations can be probematic. It’s mostly when the hardtop is on; in the summer when the soft top is on I barely notice anything.
Growing up with station wagons in the family, this is not news. You just can’t drive around with the rear glass down even with side exhaust. The fumes will still suck into the vacuum behind the moving car and into the open window, even if the glass is just cracked open. The vacuum phenomena caused dirty back windows on wagons until car makers eventually put airfoils at the rear of the ubiquitous chrome roof luggage racks back in the day. Those would help keep the glass clean but did nothing to prevent exhaust fumes from coming in.
Cracking the front windows might / should help change the variances in pressure zones so that the interior of the vehicle doesn’t act like a ‘vacuum’ for the exhaust fumes, yeah? Maybe?
Nah, unless you’re taking the windshield out, your impact will be minimal.
I had a ’90 caprice wagon that dumped its exhaust in front of the rear axle and it was no less susceptible, regardless the window configuration. For perspective, think about how much air a 6 inch tall vent window sticking an inch out could pelt you with and compare its size to the entire vehicle’s frontal area.
Just need to change exhaust to smokestacks.
“Why didn’t Toyota engineer a side-mounted exhaust for the 4Runner?”
Never mind that, why didn’t they include the wind-down rear glass in the BZ4X?
Yup.