Cars can sometimes seem to work almost through black magic. Sure, most of us know that engines largely work through the principles of “suck, squeeze, bang, blow” and missing one of those can cause a no start condition. Still, you can run into some weird engineering that just makes you go “huh.” What’s a piece of car engineering that makes you scratch your head?
Most of my cars are of the German variety, so I get to sit there and think about odd engineering decisions all of the time. Sadly, I rarely get an answer to what I’m confused about, but maybe I can expose you to the same things rattling around my head.
Let’s take a look at a 2008-2015 Smart Fortwo as an example.
Smart Fortwos with the standard transparent roof get a giant roof panel made out of polycarbonate from Webasto and Bayer Material Science. When the second-generation Fortwo made its European release in 2007, this roof was a huge deal. The previous Fortwo had a glass roof that was prone to shattering, but this new panel, spanning 1.2 square meters, was then the largest polycarbonate panel put into production.
The Makrolon AG2677-branded panel was pitched as better than glass. It didn’t shatter from rocks, weighed a fraction of glass, and maintained amazing clarity. The problem was that somehow, these panels began cracking from the inside out (a process known as crazing) often as early as just 6 months in. In theory, the panel should have been able to stand up to the abuse. They had UV coatings and data sheets suggested the panel wouldn’t start to break down until around 291 degrees.
Yet, these roofs began cracking and delaminating left and right only months in. Webasto tried reformulating the polycarbonate, which made the roofs last from a handful of months to a few years, but they still failed, anyway. It’s been so many years since I last saw a Smart 451 without a damaged roof that I’m sure the only undamaged 451 roofs out there are attached to low-mile garage queens. It’s such a common problem that I had no issue finding a Smart for sale with a failing roof:
That’s just one example of strange engineering. I could prattle on all day about how my Volkswagen Phaeton’s HVAC blower motor is dead and for some reason only Volkswagen can explain, I have to remove the windshield wipers to replace it.
Stephen Walter Gossin has his own example. Remember that expensive, yet somewhat rusty Toyota Camry that Thomas wrote about? Gossin noticed how the exhaust is pretty goofy:
Yep, there’s a U-turn in there to connect to a catalytic converter. Gossin says:
Is it just me, or would placing the exhaust flex pipe further aft negate the need for that U-turn off the cat-converter? So weird!
His other thoughts:
Possible logic #1: The only logic I can think of is having an equal length of exhaust tubing from the ends of each exhaust manifold to the flex pipe, but even that seems like a straaatch to add that extra metal/material/cost and weight.
Possible logic #2 (yes, I’m still a-head-scratchin’): Maybe moving the flex pipe aft creates too much fore exhaust system weight and thus, too much pressure on the flex pipe. Still unclear and confusing either way.
I don’t have the answer to that question, but maybe you do. Also, what other examples of weird engineering have you found out there? And to make this a little harder, the existence of the Tesla Cybertruck is too easy.
1989 Cherokee – replacing the starter involved scraping my hand against sharp sheet steel.
Really? I’ve had the starter in and out in my 90 Comanche and don’t remember sharp sheet metal in the way. That said the one SAE bolt and one metric bolt holding it in was special.
GM engine accessory access. 1988 W body. Alternator replacement needed 2 universal joints and 12″ extension or an excruciating amount of time with a box wrench. You removed the upper motor mounts and tilted the engine towards the radiator to access the rear plugs. Side mount battery terminals.
1975 Chevy Monza with the 4.3 ltr V8. Same process, loosen the rear motor mounts to be able to reach and change the rear spark plugs.
Man- recall some convoluted rwd V8 plug assess around the brake master cylinder, but that takes the cake.
The windshield / headlight washer reservoir on the e82 1 series is inside the fender between the wheel and the passenger door. When (not if) you have to replace one of the washer pumps (or the level sensor because you were foolish enough to use something other than genuine official BMW washer fluid concentrate), you have to pull the wheel, fender liner, and the passenger side turn signal repeater (the wire for which will hang up on the upper locating hook for the washer tank).
I didn’t even bother on my F22, ended up paying an indie a good chunk of change to do it.
My e39 M5 was the same way. I remember changing about 4 pumps in that darn reservoir.
E9xs are the same. Which considering an e9x is just a stretched e8x is not terrible surprising. I have one of each.
There’s not enough time in the day to talk about some of the Volkswagens and Audi’s I’ve experienced…
Like Maybe Audi V8 everything placement?
I never made it to that layer of hell… an a4 V6 quattro and a friends jetta tdi were enough of a nightmare to realize the error of my ways. Then said friend gets another jetta tdi to turn into a lemons car and a tuareg tdi for himself. Talk about stockholm syndrome…
The Pioneer:
I am a car nerd of a certain age, and at one point purchased a used Pioneer pull out radio from a coworker at the quick-lube shop . He recommended I get it professionally installed, as “it was tricky”. I’d already done a few car radio installs, so I scoffed it off, but following standard speaker wiring could never get all four speakers going. From memory I had to wire the fronts and rears in series off of the left channel and crank the balance all the way over.
Jag XJS v12… the low pressure hose of the a/c system runs mid-banks atop the engine to the very small space between engine and firewall. To service the connection of hose to evaporator, two crowfoot wrenches are required. If one slips for reasons, the tube off the evaporator is twisted and will leak. That would lead to removing all the interior ahead of the seats as the evaporator is the first bit attached to the firewall.
I’m about to take my 1996 XJ12 in for A/C that’s not as cold as it should be. I will ask my Jaguar mechanic if it’s the same for my car, which is among the very last V12s Jaguar ever built. I understand the XJS and the X300-series XJ were on different platforms, but it’s not like there was an abundance of access on the X300, either.
As a kid/early teen in the mid 90s, I always gawked at the fact that you could get a V12 Jag for relatively cheap. Reasonable even. I was young and stupid, and Dad never let me try to even attempt a purchase. The old XJS’s used to go for high school kid money in like ’98. Dad knew just from general knowledge that it would be the worst idea ever for a 16-17 year old. I didn’t understand how bad cost of ownership on something like that could be, blinded by cylinder count and style.
The molded right into the intake coolant outflow fitting on the Ford 4.6 V8.
From what I can tell, other manufacturers make similar parts as a standalone piece, so when it invariably cracks after exposure to high temps, it’s easy to replace. Not ford…you have to replace the entire manifold. At the very least, my new one has that fitting made of cast aluminum instead of plastic now.
IT was probably a TSB, but since it often failed after warranty, they conveniently did not recall them. Kind of like the intake gaskets on GM 3.4 engines.
I bet you’re right. Mine failed about 15 years later, so I guess I should be glad it was that long a run.
Mk V Golf/Jetta/Rabbit A/C compressor control module- where is it?
The Internet says there were several different compressors used, but the controller is the same. It basically says, “look in these three places”.
Well, I looked in those three places, and it wasn’t there. I looked in every other place that I could get to, and it wasn’t in any of those places either.
I pulled the glove box out- nope. I pulled the dash apart- nope. I laid up-side-down and used the brake pedal as a pillow so I could get under the dash. Was it there? Nope.
I pulled out every piece of interior trim that contained a cavity big enough to house this compressor controller. Did I find it? Nope.
I went back under the hood and tore off everything that was big enough to hide the compressor controller. Did I find it? Nope.
It’s their revenge for losing those wars.
Must be the same engineer who designed the BMW TPMS system radio receiver. Across the various bodies and years of the e9x 3-series, it could be in any of about five different locations. In or under the car. Happy hunting!
The F-chassis BMW’s are universally plagued by lifeless steering, except for the M4 GTS. The GTS is praised for almost-hydraulic levels of steering feedback, with more precision and granularity than any other BMW.
What, then, does this 6-figure, caged winged, water-injected track-day weapon feature that fixes all the steering problems? Is it custom spherical control arms? A bespoke steering rack? Aggressive alignment that wouldn’t work on the street? A little, yes. But that’s not where the feel comes from.
It steers well because it’s missing a little rubber disc in the steering column called a torsional vibration damper plate. All non-GTS cars across the entire F-chassis era have this rubber disc between two sections of the steering shaft.
This component, presumably designed to make the X5 0.2% more comfortable on the highway, is replaced by a metal wafer in the M4 GTS.
The M2, M3, M4, M5, M6 and every M-sport trim beneath are subject to endless bitching about the steering feel by every journalist, critic and owner, because Bavarian Motor Works, the makers of the self-proclaimed Ultimate Driving Machine, spent real Euros to delete all remaining steering feel in the base models, and couldn’t bother to un-spend that money on the sport trims. Unforgivable, if you ask me.
I had no idea. And, yes, I did think the steering was lifeless in my ’16 535i xDrive M Sport.
So was my M235i, my quest for ways to fix it was how I found out about this.
There’s also a tuning element to the steering feel. My 2016 M4 felt better in every way after coding it with the GTS steering, DCT, and differential tuning. I also changed the MDM traction control setting to the euro version that wasn’t nearly as restrictive as the US one.
They did it VERY intentionally, based on customer feedback. The average customer doesn’t want to feel anything through the steering. To which I say, “go buy a damned Lexus then”.
Don’t forget, that F3x Series that we all love to shit on was the best selling 3 of to date, and not by a small margin.
So the question is, can you retrofit that solid hunk of steel? Asking for a friend…
I’m sure you can fabricate one, it’s a fairly simple plate. If nothing else, take an original one and turn some inserts on the lathe to replace the rubber bits.
Brittle plastic engine parts on Mini and BMW cars. Other companies know of plastic that doesn’t shatter at 5yrs, can’t you at least ask your suppliers for something better?
Also, F-150 water ingress protection. Or lack of it. It was way easier for them to switch to aluminum to stop a truck from fucking rusting instead of using proper weather-stripping design like everyone else. . .
The brittle plastic isn’t limited to the engine if you live somewhere that gets warmer than 85 degrees during the summer.
On a 2024 Sonata N Line the engine cover has to be removed to access the oil fill cap. This is silly considering the regular and hybrid engines have cut outs in the cover for the cap.
Hmmm, on my car you have to remove the oil cap to remove the engine cover.
It could very well just be some silly afterthough, but it might serve a purpose: The more powerful N-line engine generates more heat both due to its capacity and intended use, so it’s possible that the cover acts as a heat shield to keep the sheet-metal on the hood cool, and the cut-out for the oil cap would compromise its function. I wouldn’t accept this on a ground-up performance car, but when you put a new engine in an old chassis, you sometimes just have to make do.
Very plausible. Good thinking.
the exhaust pipe is that way so that the runners from the individual headers are equal length to the y where they join. If they moved the Y back to avoid the U-turn, they’d no longer be equal length and would cause issues with unbalanced internal EGR between cylinders
I also imagine it makes it easier to package the drivetrain in different bodies, as the headers meet under the engine and don’t affect the shape of the floor pan or anything else.
Daughter’s New Beetle with the 2.5 liter engine. One belt runs from the crankshaft to the A/C compressor. Everything else runs off that. The compressor seizes and you can’t drive the car. Also, this car has two, yes two, oil pan gaskets. One is easy to get to. The second requires removal of the transmission. Guess which one developed a leak?
The BMW N52 having the PCV valve built into the valve cover
And the N55, and the…
The S55 in my M4 has been flawless for almost 90k miles with nothing but maintenance except for that stupid valve which failed at ~80k miles.
OR, wiring said heater directly to a 30amp fuse. It is always on with the engine on. I just had the in-line fuse installed via recall last week. So stupid.
I had the original recall done on mine several years ago
I didn’t, and the PCV valve is still original! AND, they didn’t change it because it “tested good”. Thanks BMW. Left the dealer with the rear airbags fully deflated and a smug shrug from the tech. I’m so done with German cars at this point.
The battery on the 90’s Dodge Stratus (and obviously the other cloud cars) was placed behind the wheel well liner on the driver’s side front. Yep, this means to replace the battery, you need to remove the wheel and the wheel well liner to get to it.
Absolute suck and completely freaking stupid.
They did this on my mother in laws Sebring convertible too, as did both my father in laws Journeys. Yes, after no end of electrical and transmission issues on his first Journey he traded it in at 5 years old on another Journey.
That they continued this practice all the way into the Journey is… well sort of typical for Chrysler or whatever entity owns them at any particular time.
Some people can’t resist the siren’s song of cheapness that the Journey sings.
I’ll defend them in that they were cheap, could sit 5-7 and had a new car warranty. But I can’t defend buying the second after all the problems with the first.
I did a starter motor in one of these years ago. It’s directly underneath the intake manifold. I imagine the book says to remove the intake and the job is cake, but I was 18 and did not want to disassemble my girlfriend’s car to that extent in her mom’s driveway.
I can certainly understand that, lol.
The battery placement on a 2017? 19? Ford Escape. It’s 2/3 under the dash, with just the barest ability to even disconnect the positive terminal. To actually take it out you’d have to pull all the air intake out up to the throttle body. Absolutely bonkers.
Putting every function in the damn car on a giant tablet
Gotta make cars more comfortable to the generation that has grown up with smart phones and tablets their whole lives /s haha sure it is more of a cost thing at this point shove everything on a screen so no more buttons, switches and stalks to spend money on.
Exactly correct.
It’s not often OEMs get to make a change that both saves them money and also appears more “premium” to customers (blog commenters excluded).
Between grocery store self-checkouts, airline kiosks, and those mall map things I’m honestly surprised touchscreens still feel “premium.” Sort of like how people are conditioned to react with blind rage to an automated voice because so often they tell us, “Thank you for calling the fire department. We’re sorry, but all of our available agents are busy. Press one to receive a call back…”
Joke’s on manufacturers, because that generation can’t afford new cars
That reminds me of Scion lets try to appeal to young people who cannot afford new cars
Well they are doubling down on this it seems, more and more seem to be just two crappy tablets anchored to a flat dash plate.
LT1 Optispark. Nuff said.
Also, putting starters inside of things like valleys or bellhousings. Stop it.
Or in a similar vein, whatever ford did to make the 5.4 Triton obliterate spark plugs.
Also, Dodge Journey 12V battery location, just… why
obliterate, no, spit them out of the engine taking out the too few threads engaging the spark plugs, yes.
the triton cam phaser bearing surface not having an actual replaceable bearing is an issue, but one of many with those time bombs
My mother had the miracle 5.4 in her Expedition. She sold it with about 270k on the original engine, and even more surprisingly, the original transmission that NEVER had a fluid change. I remember her boss at the time was so bitter, because he had the same truck and was on engine #2 and transmission #4 at less than 150k lol. Mom’s truck burned a little oil and had some leather issues, but was otherwise solid as hell. It must have been literally one in a million.
My brother has over 320k miles on his 2006 F-150 5.4. He’s doing the cam phasers and everything timing related right now before he sends my niece off to college with it. Probably 100k+ miles of that was towing and he’s on his 3rd or 4th transmission (2 of which were replaced under warranty). He now drives a 2024 power boost that he’s hoping will last just as long.
Hope it works out. some say the only solution is a complete replacement long block
Oh and any fuel pump you have to drop the tank for. Access panels aren’t hard to make.
My dude! I will walk with my people.
https://www.theautopian.com/why-people-cut-holes-into-their-cars-trunk-floors-even-though-it-could-kill-them/
Hah yeah I dropped my tank when I did the Ford 9in swap on my firebird and replaced the fuel pump since I was already pulling things apart might as well put a new higher flow on in there. If it fails though not sure if I will cut an access panel or not.
That reminds me of the Hyundai Elantra (Touring) that I owned, where the gas tank needed to be dropped to replace the cracked EVAP canister. What a PITA.
Better, any fuel pump where to replace the pump, you have to replace the entire fuel tank, as it’s all one sealed unit including the fuel lines to the engine. Basically any car with a “PZEV” designation.
And they don’t make the Optispark anymore! You can only get them aftermarket, and they’re almost universally garbage, MSD version excepted.
i think the Optispark had that starter placement issue you suggest.
The starter just needs the y pipe dropped. It’s in a normal place though.
I’ve rambled about this before so I’ll keep it brief, but the 2010 era Nissan Versa intake manifold is extraordinarily stupid. To replace spark plugs you must remove the entire intake manifold, all intake tubing, the Throttle body (theres a bolt holding the manifold on hidden behind the TB) and about 4 hoses attached to various things.
A simple 20 minute coil and plug job takes 2 hours. and requires both a new intake manifold gasket, and throttle body gasket. I’m certain renault merger shenanigans are at play, but I have never seen any other FWD 4-cyl made in the last 25+ years that has coils and plugs blocked by the intake manifold. Also the dip stick gets in the way of one of the manifold bolts, because of course it does.
Yeah I worked one someone’s sentra before and it needed a new accessory belt and holy hell trying to get to the tensor was near impossible with the passenger side wheel and fender on. Like I shouldn’t have to take all of this off just to replace a belt.
Every modern Nissan I have had the misfortune of being in, under or around, it becomes extremely apparent very quickly why they’re “so affordable” compared to the competition. The Build quality of a 4th grade science fair project is hardly a plus, even if it does make it cheap.
mention Nissan and then no mention their uncooled and poorly made CVT?
This is 100% Nissan, stupid 4 cylinder we had to put in Laguna, Mégane and Scenic .
Nissan engines only trouble.Renault F4R (T) much more power and reliable K4M reliable.
Had timing belt but changing this is less off a problem than stretching chains
I owned a 1996 Maxima 5sp (which I actually miss), and the number of times simple procedures required a wheel to come off was really annoying. I can imagine they only got much worse from there.
I once owned a 1983 Mazda GLC. It needed new front rotors, so being the driveway wrencher that I was/am, I took it upon myself to do the job. After removing the wheels and calipers, I expected the rotor to just slide off. Nope! They were attached to the BACKSIDE of the hub flange. This meant you had to press the hub out of the bearing, ruining the bearing in the process, to get the rotor off. WHY? WHY? WHY?
Since I only paid $400 for the whole car, I put some grease on the bearing balls and pressed all back together again with a new rotor. I was NOT going to spend money on a new bearing. It worked fine for the next several years.
We bought a 1983 GLC brand new. It really did a great job of being just enough.
We got ours 10 years later. It was a great winter beater… once I got the brakes fixed.
Not Toyota (bless their hearts). But Nissan yes.
My first car was a 1981 GLC wagon that I inherited from my mom. Even though she bought it new, it needed a brake overhaul after 5000 miles. Fortunately I never had any brake issues while it was in my care. Just the thermostat, radiator, fuses…
That was common practice among most of the Japanese Manufacturers back then. I know Honda and Mazda did it, and I think Toyota.
Why – oh why? – would you run the waste disposal system right through the recreation area?!?
Oh wait. This is stupid AUTOMOTIVE engineering.
Carry on.
Took me a minute to realize you weren’t talking about a campground.
Don’t get me started on teeth. “Wait, so they don’t grow back, but if something goes wrong with one, you will be in excruciating pain until you fix it or it kills you?”
COTD material
I believe this is the technical manual description of EGR
I’m betting that that Camry’s exhaust is the way it is to give equal-length secondary lengths off of each manifold. Packaging considerations presumably meant that was the easiest way to do it.
If you *only* have to remove the wiper motor to get to a blower fan, you’re lucky. At least you don’t have to remove half the dash, etc.
First baffling engineering decision that comes to mind is the headlight mounting on my 911 SC. US cars had sealed beams mounted in the bowls in the fenders using several tabs – robust, and makes the lights easy to install and aim. Non-US lights have the entire lamp assembly secured by hooking the lip over the flange around the bowl on the fender, plus a single bolt at the 6:00 position. Bafflingly crappy for a company that made a bunch of other well-thought-out decisions on the same car.
Agreed on the equal length sections off each bank going into the flex pipe – that was my 2nd guess in our team Slack channel.
I wonder how important having equal exhaust lengths for each bank truly is in order to justify the cost. Intriguing.
It can be pretty important since the exhaust runner length determines when exhaust pulse from one cylinder opening it’s exhaust valve reach the others – if it happens for most cylinders right after their own exhaust valves close, then those cylinders will have low internal exhaust gas residual, faster flame speeds, easier-to-ignite mixtures, and lower knock. If it happens for one or two cylinders right before their own exhaust closes, then those cylinders will be more prone to knock and have slower combustion speeds beforehand. This gets even more important once you get into engines with variable valvetrains that will be changing on the fly. So if the exhaust runners aren’t equal length, then you either de-rate the whole engine to account for the worst cylinder, or you dont and eventually have consistent warranty issues with that cylinder.
Quality content there.
I’m guessing that the design chosen worked best in NVH scores.
Tell me more.
If I’m buying a Camery, it is expected that the drivetrain in operation is not sensed by the operator. No buzz, moan, groan or drone will find a way into the driving experience.
I guess what I was hoping to hear was why a design like this would provide lower NVH.
As stated, my estimation. Your background may offer other insights.
I may be a bit biased here as a (former) engineer myself, but just putting out there that almost all the time, the engineers themselves are aware of every single one of the issues that you’re going to bring up in these comments, that they brought it up to management themselves, and they were shut down over a few pennies in BOM cost, a few seconds of added time on the assembly line, and/or a score slightly too low on a DFMEA.
Yeah I have worked at a lot of different places where it would have been a big benefit if engineers actually worked with ops/techs even if just temporarily. When I worked in oil research they did actually have the new developmental engineers (so normally kids fresh out of college) work on swing shifts with ops/techs for a few months so they could actually understand physical process. Was funny though seeing kids that didn’t even know how to turn wrenches but this was very helpful for them vs engineers who never worked along with the techs that didn’t understand how the real world work goes.
I have participated in/supported initiatives like this everywhere I’ve worked. Engineering can’t be done only at a desk.
Oh for sure but I have worked with people that think it can. Some people just not willing to get their hands dirty which I understand but should at least be at a physical location at times to see the work that will be done and how somethings just are not practical.
This seems to be extremely true for US design vehicles, the number of internet rants I have seen about Ram oil plugs draining directly over sway bar, and similar other dumb cost saving measures is staggering. Meanwhile, my newly acquired GX 470 has a plastic guide added directly below the oil filter that flows thorough a hole in the skid plate to make sure you don’t make a mess when doing an oil change, and you don’t need to pull the skid plate to do it. Attention to detail and that bit extra in manufacturing cost goes such a long way during ownership.
Agree to an extent, but I would not take this generalization too far though.
There are plenty of corners cut on my Toyota, some of which cause me no small amount of frustration.
Anytime there is a bolt and there is no way you can get any kind of tool on it or the bolt is to long to be taken out. Why engineers why?
Because they likely prioritized speed of assembly over servicing. That bolt you are cursing was likely easy to access and install on the engine before the engine was installed in the car, but is now impossible to access with the engine in the car.
Oh I understand that I still hate it haha
Stellantis’s new generation of vehicles, they are so freaking wired up that the silliest thing will cause a complete loss of the vehicle. I had a customer who’s wrangler demanded to be put in park, so she pulled off to the side of the highway and put it in park. Once in park, it would not allow itself to be shifted back to drive or reverse. One minute everything fine, the next, completely stranded. The culprit? A bad solder in the Airbag module.
Yes, safety and proper functioning SRS is essential, but the idea that if one wire goes bad you are stranded on the side of a 4 lane interstate is absolute insanity to me. No redundancy, no failsafe, just stranded with a dead 60,000 dollar rig.
This also isnt isolated, this can happen just from a random fuse not being pushed in all the way.
We buy new cars exactly so shit like this doesnt happen. I think we have enough technogoly now to engineer an emergency drive mode, so someone can at least get to safety in the event of a failure. It’s baffling.
I saw on r/justrolledintotheshop a new Wagoneer that had its whole interior gutted. I mean everything. Complete body harness replacement because something dumb wasn’t working, like a rear seat infotainment screen or a usb charger or something.
That’s about all of ’em these days to be fair.
Sounds like my Audi TT