I’m willing to bet genuine, damp money that this has happened to you or someone very close to you at some point: on your car or one of your cars, likely one made in the past 20 years or so, you’ve noticed an annoying flapping sound or a scraping sound. It gets progressively worse and is louder and more annoying the faster you go. It’s awful, and by now I suspect you know exactly what it is: big hunks of plastic coming loose from under your car. These plastic sheets and panels are sometimes known as splash shields or aero shields or underbody shields, something like that. They’re also one of the worst-engineered components of modern cars and are a global embarrassment that so far no automaker seems remotely interested in doing anything about.
Years ago, I wrote about what I felt was one of the biggest engineering failures in the automotive world, the scourge of sagging and falling headliners that plagued cars from the 1970s to the 1990s. I think the industry-wide epidemic of falling splash guards easily meets or even exceeds the Great Headliner Failure of decades past; the problem crops up on cars all across the automotive spectrum, and doesn’t seem to be restricted to inexpensive cars. Premium cars seem as likely as any to have their underbody plastic sheeting tear and break loose, which gives the problem a nice egalitarian character, at least, as likely to plague Mercedes-Benzes as a Hyundai.
It’s probably worth mentioning just why these shields exist in the first place, and there’s a number of very valid and reasonable explanations. They provide some aerodynamic benefit, helping to smooth out the path of airflow under the car, they prevent water and dirt and grime and other crap from being flung up into the engine bay, where it could potentially cause electrical issues or increase wear on belts and hoses, and, well, I suppose that’s pretty much it. They provide some degree of protection from scrapes and bumps, but they’re not actual skidplates, so your oil pan may still be boned if you whack it hard on a rock, plastic shield or no.
I was going to provide some links to people talking about the issue of loose or falling plastic shields, but a bit of Googling soon revealed the folly of that idea, because there are so many examples. If you just type into Google the words “plastic cover under” – not even mentioning anything about a car – you get results like this:
Look what you get: loose, fell off, came off, hanging, dragging, the state of plastic covers under cars is not a good one.
I tried one with a normal browser window and one in incognito mode, just to be sure the suggestions weren’t influenced by my previous search history, and, as you can see, even without specifying car, Google knows what’s going on, because vast numbers of people have been asking these questions, since these stupid plastic shields have been tearing off cars all over the place.
The reasons why this happens isn’t exactly rocket surgery: the plastic gets worn and tears, especially around the points where the plastic shields actually attach to the structure of the car, where it’s usually secured with plastic clips and tabs and other bits of degradable, consumable hardware. Plus, many of these shields require removal to do basic maintenance like oil changes, and that increases wear and tear on the too-fragile fasteners that hold these things on.
They’re also usually a pain in the ass to get out of the way when you just want to change your oil, and I suspect many get ripped out in during these processes.
Tomorrow I’m supposed to help a friend remove one of these shields from her Honda Fit; it’s one I’ve repaired with zip ties before, and I can’t even recall just what number of times I’ve done exactly this same job – ripping out a raggedy splash shield – for one of my own cars or a friend’s car, often done with some amount of frustration and anger in a parking lot, at night.
If your car has these plastic shields, it’s not really a matter of if it’ll get torn and start flapping around, it’s a matter of when. These are not really a solved engineering problem, by any means. They all fail, and they all fail in essentially the same, annoying ways. The holes for the plastic fasteners rip, the panels themselves rip, everything sags and flaps and oh they’re just stupid and terrible and nobody likes them!
My older cars don’t have any of these things and they survive, somehow. And, I’ve yet to meet anyone who has yanked out big chunks of ragged charcoal-gray plastic from under their cars, flung it in a dumpster, and somehow regretted it. Once these things are ripped out, perhaps your highway fuel economy drops by half a mile per gallon, perhaps your belts get more wet than before, but generally, quality of life improves.
There have to be better ways to mount these things if they’re so important, but I doubt that will actually ever happen, because that would require more money to be spent. Fastener holes could be reinforced with metal grommets, or some manner of quick-release clamping system could be used to retain the splash guards, but is any carmaker going to invest more money to make that happen? I doubt it.
From their perspective, this is hardly a problem at all. The shields start to fail long after the car has been purchased (generally) and the customer either rips the floppy plastic out or pays to have a new sheet installed. The carmakers have no downside here! This is just one of those side effects of capitalism where making something not suck just isn’t worth it, and the consumer can just shut up and deal with it.
But that doesn’t mean we have to like it! We can kvetch, loudly and boldly, and let the automotive world know we’re on to them. Underbody plastic bullshit is garbage, piping hot, cream-frosted garbage, and we’re doomed for the foreseeable future to have our cars, at some unpredictable, unexpected time start to make horrible flapping noises, requiring us to shimmy under the car and sweatily cut and yank and grab and pull out all of that near-useless, degraded plastic, and fling it into the trash, angry at the waste and senselessness of it all.
So, I’m calling this as The Biggest Modern Automotive Embarrassment. Plastic splash guards and underbody shields may be engineered for their purpose, but it appears no attempt is made to consider the longevity of these things, or how they may fail. And the result is hassle for pretty much every car owner, at some point.
Screw these things. We can do better. I have to believe that, I just have to.
I think the inherent materials problem combined with cost will never surmount the issue outside of enthusiast applications such as offroading or racing. Metal is better but weighs more and isn’t as pliant.
Plastic under shield panels are wear items by their nature.
I must be the only person who does
any maintenance on these.
$7 box of plastic clips on Amazon will keep these from falling off due to worn out rivets.
I’m also careful when removing them UNLIKE the local quick lube who just rip on these like cave men.
In fact, that last point is probably the #1 reason for these coming off, if not from scraping your car on the street too much.
this is a PARTICULARLY sore spot for me at work; there are some very well designed ones that are maintenance friendly like from Hyundai/Kia, Mazda, Toyota, Honda, and Jeep; and then there’s Ford and Nissan; whose splash shields make me want to tear my hair out because their Engineers couldn’t be bothered or were told “NO” by the bean counters to have maintenance access holes in them.
My ’07 Mazda3 had an access hole in it. Unfortunately it was like six inches away from the oil filter, which just baffled me.
the scourge of sagging and falling headliners that plagued cars from the 1970s to the 1990s
If you include VWs, you can push that scourge all the way into the 2010s.
Dodge Avengers and Chrysler Sebrings of the bailout era have the issue as well.
I had problems with these on both of my Ford C-Max (yes, I owned a C-Max twice). The first one had the front shield, beneath the engine, ripped off by a puddle of water in an awkward parking lot entrance, but I got it reattached and it only occasionally fell back down. But the second one? On a road trip from Fort Worth to Corpus Christi, I hit a chunk of tire south of San Antonio that caused the large, central cover to drop down on the driver’s side, and it ended up scraping obnoxiously that whole trip–I think a chunk of it actually wore off from friction. Unfortunately, I never got it reattached correctly, went over a speed bump at a funny angle, caught the center shield which shifted and pulled the front shield, which disconnected some of the plastic in the driver front wheel well…
Nursed it home. It poured rain overnight. Next morning, having pushed what I could back into place, I left for work before sunrise and didn’t see an entire lane of the street on my commute was flooded. I hit the water, both shields dropped and just scooped hundreds of gallons of water up into all the parts of the car they were supposed to be protecting. I made it to work, I made it home with lights starting to pop up on the dashboard…and the car never ran again.
So yeah, a pox on these things.
A couple years ago I was helping my mom move from Iowa to New Mexico. She was driving her C-Max and I was following in a U-Haul. Just outside of Kansas City the front shield failed. We made it to a gas station where I was able to do some janky parking lot repairs with camo gorilla tape they thankfully sold at said gas station. The plastic was too thick for me to rip out by hand and I didn’t have any tools, but that gorilla tape held for the rest of the journey thankfully. I hate that stupid C-Max, but she likes it, so whatever.
Wow, I’ve never had a problem with these guards and I and most of my cars must be a weird fluke after seeing the comments here, but yours is just insane to me. Who thought it would be a good idea not to layer them like a shingle so the only way part 3 can fail like this is parts 2 and 1 have to first.
A Semi blew a tire in front of me, and I ran over the carcass with my 2021 Mazda 3. The tire destroyed the shields, but they protected the radiator, oil pan, fuel tank, exhaust, and suspension components. Glad I had them. Now I just have to wait for the repair shop to source new ones . . . a long wait.
Try quirk-parts.com or onlinemazdaparts.com. They have been my go-to for parts like that for my Mazdas.
And expensive too
I ran over a chunk of tire ar highway speeds, and now the car is rattling constantly. I changed a couple clips, but that wasn’t enough.
At the very least, these things need to have some kind of smushy gasket to absorb the vibration.
Thanks for bringing this “feature” to the public consciousness.
I pulled this off the underbody of my old e46 BMW 325ci, drove through a puddle, and immediately had my headlights short on the right side. Turns out it has been keeping some worn wiring just safe enough.
Yep. My 2008 Mazda3 that I drove all through and just after college had a hole in the lower right fender well of its splash shield and it caused my A/C and serpentine belts to be directly exposed to water, rocks, dirt, etc. Needless to say, I ended up replacing those belts and the subsequent tensioner lot sooner than most people had to.
“LEXICON VALLEY“There’s a Number of Reasons This Headline Could Infuriate You”
https://slate.com/human-interest/2014/04/a-number-of-the-phrase-is-treated-as-both-singular-and-plural-and-preceded-by-there-s-there-is-and-there-are.html
The real shame about these is that no one ever seems to notice the horrible scraping sound as they drive and cares/bothers to fix them. They do their job fine, but like everything else in the car, they need to be maintained
It’s like when you get in an uber and hear all the suspension rattles and knocks…. Like, does that not concern you?
The problem is these things are held on with the shittiest plastic clips that always break. It seems like you can’t do an oil change without breaking at least one of them.
My wife’s MINI has a shield under the engine fastened with tamper proof torx(!). To discourage DIY? Seems like a perfect choice to piss off everyone. Is a DIY-guy going to bring it to the dealer for that sole reason? Probably not. But he (I) will be pissed he has to order special tools for a friggin’ oil change, which he’ll only discover when the car is in the air. Similarly, the techs at the dealer will be pissed they have to get the same tools.
Frankly, I’m relieved that my dealer didn’t throw all that crap in the garbage when I was coming in for ‘free’ (include in purchase) oil changes.
The overuse of tamper-proof torx bolts is one of my minor-key annoyances. At work, I’ve noticed the bathroom stall panels are mounted to the wall with such. Huh?
MINI’s built by BMW, they default to Torx for *everything*.
I’ve never had these come loose on any vehicle I maintain but I see them flapping in the wind on other cars almost daily. I would wager its mostly due to mechanics not putting them back on fully combined with losing or breaking the plastic clips and not replacing them. That and people running over crap and damging it.
On my new 2022 GR86 I noticed the plastic fasteners are so much easier to remove which I love. Removing older fasteners is usually a pain and likely leads to them failing much quicker as you often have to pry them off in a way that wasn’t intended.
I do have a box of replacement fasteners for my older cars so that definitely helps keeping them fully dressed.
Never had them come off, but the one on the mk3 Focus was covered in some kind of weird fabric-like thing. It seemed like plastic underneath, but it might have been entirely some kind of odd fibrous material that got worn like an old wool sock after being scraped. It was secured with basic rustprone torx bolts of very course thread into plastic with a couple clips being metal at the front. Removing it seemed to have no effect on mileage. The GR86 is proper metal with a separate, small cover under the oil pan drain plug. It’s installed with 3 bolts that thread into metal clips, so that 2 can be removed, one loosened to swing aside the door to drain the oil (plus the oil filter is on top). THIS SHOULD BE THE STANDARD! And this wonderful little car that must make virtually no profit at its sales volume and price cost several thousand less than the most basic Civic hatch I could spec with a manual.
I remember my 94 XJ had a one under the engine that was made of some sort of fabric. It looked great covered in oil and starting to rip.
Do Mazdas seem immune to this or have I only been around good ones? I can think of an example for just about every other manufacturer, but I can’t seem to remember seeing any Mazdas dragging their shields. As far as I can remember they also don’t need to be removed for regular maintenance so maybe that’s why.
My 3 didn’t fail, but it was designed by morons as what looked like an opening for the oil filter (annoying canister type) was way off where it needed to be. Hole saw fixed it and not having to remove it for oil changes probably kept it from deteriorating.
Waaaay back in the early 80s the original water cooled Vanagons had these in metal to protect the pushrod tubes and shield various things under the engine. Behind the plastic grill were two fiberboard pieces designed to channel air to the radiator. All worked fine when maintained but after 20, 30, 40 years they get to be replaced.
The advantage of the metal variety is, properly tightened, they don’t rattle or fall off. Dumb mechanics can mess with that but easy enough to complain and they’ll stick the wrong screw in there which works well enough.
I’d rather have metal w/ metal screws and clips than throwaway plastic.
I don’t have a sagging problem on any of my vehicles, partly because I replace any fasteners that have broken off and partly because only one vehicle has plastic ones – the others have steel skid plates.
My neighbor’s $85k F150 is constantly dragging the panel that goes under the engine and transmission. Ford uses a flimsy quick-release fastener that is spring loaded and doesn’t seem to like to stay fastened. I will often let my neighbor know when the panel is hanging down, almost always with the response that he had just reattached the things a day or two before.
The underbody cladding on my Q3 is some kind of fiber material, feels like outdoor carpeting on a hardened backer. There is one corner behind the right front wheel where there is no fastener so if I nail a big enough puddle a small 6×6 square of the panel will bend downwards. It will then only touch the ground if I hit a large enough whoop that the suspension compresses far enough for it to so sometimes I don’t even notice it bent out of place for days (weeks?) It is unable to be “fastened” back up as it actually seems like it shrunk kind of like those fiber under hood insulation which always seem to shrink to where the fasteners can’t hold them anymore. I can still tuck it back up so the leading edge is kind of behind another piece of plastic which is good enough for me.
Also, I had (a number of) Mk3 VWs and they seemed like they didn’t have enough cladding under the engine bay as you could hit a puddle big enough on the right side and turn the belts into a squealing mess
I bought an aluminum skid plate off Prius Offroad to replace mine. Funny enough, I’m never even under there myself; I was mainly drawn by the advertisement of an extra inch or so of ground clearance, plus the hope that if I ever hit one of those blown tractor trailer tires on the highway, it’ll only damage the plate and not anything above it.
Not looking to test that theory, but I’m cautiously optimistic, at least compared to the idea of one flying through the plastic cover like a tin can.
I briefly tried selling the used engine cover only to realize that you could get them new on eBay for $65.
My fuel economy might be slightly improved too, but this thing is still in the 41-45 range in the summer so it’d be hard to tell.
The skid plate is just held in with four 17mm bolts already in the frame, and it has an oil change door in it. So I should be good to go whether I have to take it off for something or not.
My old Cruze had a great big shield. It worked really well for keeping grit out of the engine bay and for general aerodynamics. Chevy quick lube grease monkeys would slop oil down the front of the engine during oil changes. That would eventually build up in between the aluminum heat shielding and the plastic. Some fires happened and a recall initiated. GM’s “solution” was to cut away the bulk of the shield. It absolutely made the car worse. Less stable on the highway, noisier and worse fuel economy.
Believe it or not, people kept those giant plastic shields. Yes they were absolutely a pain to work around. Thankfully they didn’t need to come off too often.
I think the undertrays are fine as long as people keep the oil change monkeys away from them. My mom’s car had one that had to be removed to change the oil. Not a big deal, really. She drove up to visit and mentioned her car was making a weird noise. I put it up on the lift and sho-nuff the under tray was hanging on by the last three or four screws and was flapping in the breeze when driving. I zipped over to Oreilly that, of course, had all the right OEM style parts to fix it up. She raised hell with the oil change place when she got home.
My DD has one but they put a trap door in it for doing oil changes so no big deal there.
I actually added an under tray to my fun car for aero purposes (seeing if it makes a noticeable drag reduction). It was a complete DIY job but I made sure the Lexan panel was held in with many solidly mounted screws and aluminum brackets so it doesn’t fly off over 150mph. It doesn’t obstruct oil changes so I shouldn’t have to mess with it often.
Enjoyed the rant. Enjoyed the style even more. It read like a collaboration between Andy Rooney and Hunter S Thompson. Thanks!
It has been posted before, but Autopian really needs to make some merch with Torch’s illustrations. A Rock Auto style magnet with the picture from this article would be perfect for my toolbox.
At least the underbody panels have some utility. The engine covers are what I don’t get.
In addition to aesthetics (obviously subjective), I was under the impression that those help keep them quieter–maybe dissipate the sound different so it’s not harsh?
Yeah, modern cars are fairly quiet, aren’t they? I mean unless it’s the point to NOT be.
I think of the covers as a by-product of our smartphone era – people want things that are sleek and minimalistic, seeming to work by magic. An ICE engine is (gloriously) not that, but give people an illusion and they’re happier I guess.
They’re fairly quiet because they are covered with sound deadening panels.
My mom’s Bronco doesn’t have an engine cover and it’s noticeable
Many of them also have pedestrian impact functions — Volvo’s are foam for precisely this reason.
I didn’t know that. Though Volvo can make any system somehow safety related.
Cheaper than the solution they had on the 1st-gen XC60… which was pyrotechnic hood hinges that lifted the hood when an impact was detected to provide clearance between the sheetmetal and the intake.
Correct, modern direct injectors are kinda noisy and those plastic engine covers often have insulation underneath for that reason.
Very interesting. Thanks for the comments.
They’re needed with today’s direct injection engines. They sound like diesels without them.