It’s a question a child might ask, but not a childish question: why is it that only hatchbacks, wagons, and SUVs have wipers for their rear windows, when sedans with trunks almost never do? Like the old saying goes, the rain has no idea how you get luggage in your car. So why should one incredibly common type of car frequently get to enjoy a wiped rear window, while another incredibly common type be denied this benefit? It’s a confounding problem, and I think I may have gotten to the bottom of it.
I’m by no means the first to ask the question; it’s a natural thing to wonder for anyone who’s driven around with a rain-streaked rear window. And I’m not the first to claim to have an answer, either. But the explanations that have come before I don’t think make any sense.
The most common rationalization is that there’s an aerodynamic justification, suggesting that the way the air flows over a car with a trunk as opposed to a car with an opening rear is different. Usually, these explanations make assumptions about the shape of the hatchback in question, often suggesting that hatchbacks have vertical or nearly vertical rear windows, which are said to get dirtier, or more affected by the rain, or whatever.
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This explanation, of course, is horseshit.
First, the idea that rear wipers are only present on vehicles with nearly-vertical rear windows is disproven comically easy. A casual glance around almost anywhere out-of-doors will reveal hatchback cars with rear wipers with rear windows running a wild spectrum of angles.
Don’t believe me? Look, here’s two cars from the same automaker:
There’s two common cars with hatchbacks and rear-window wipers. The top car has a rear window angle of about 80°, almost vertical, and the bottom car has a rear window of about 20°, almost horizontal. If the angle of the rear window is truly a factor in why a rear wiper may or may not be needed, then the range where a wiper must seem to make sense is vast, and would include nearly every sedan.
In fact, I can only think of a handful of examples of cars where the rear window’s angle would make it somehow immune from the effects of rain, and those cars tend to look like this:
I’m not buying the rear-window angle/aero argument. There’s an adjunct to that argument that suggests the presence of a trunk, an extension of a car’s body beyond the rear window, affects the airflow over the car in such a way that dirt and grime are less likely to be deposited on the window.
This explanation doesn’t ever seem to bother with the whole ‘falling rain’ business, the goddamn raison d’etre of wipers, period, but, whatever.
There’s a kernel of truth to this argument, as looking at airflow patterns over sedans and hatchbacks do sort of suggest that airflow is less turbulent at the rear over a sedan than a hatch.
Okay, fine. But that still doesn’t explain why when given two cars with nearly identical profiles, one hatch and one sedan, the hatch may have a rear wiper while the sedan never, ever will. Look at these two cars I happened to spot on the street, one sedan, one hatch, one rear-wiped, one not:
Both that Acura and that Volvo have about the same length of decklid behind the rear window, and both those rear windows are at roughly the same angle. Either one could have been engineered to be either a hatchback or have a trunk. Yet still we see that only the hatchback gets a rear wiper.
There’s also the argument that cars with trunks don’t have the room to house the wiper motor and arm assembly, but I’m pretty sure that’s not the case, since there have been a number of non-hatchbacks (rare, sure, but not unknown) that have rear-window wipers.
The wiper motors tend to be housed under the rear package shelf, and there seems to be plenty of room. In fact, one of the very few longtime proponents of rear-wipers for non-hatches, Porsche, has been putting them in cars with pretty cluttered rear ends for years.
Some cars, like the Lancia Flamina, even found room for two wipers in back. These bold, uncommon trunked cars that dare to keep their rear windows clear in the rain should make any claim that it’s impossible to mount a working rear wiper on a non-hatchback seem like the bullshit answer it is. It can be done. It has been done.
So, if all the arguments for why trunked cars (sedans, coupés) have no rear wipers and hatchbacks (or vans, SUVs, CUVs, wagons, etc) do are bullshit, then what is the reason? I believe I found it when I reached out to one of the very few companies today that make three-box-looking sedans with rear wipers.
I first noticed the cars when I was in Barcelona, where Skoda taxis are in use:
That sure as hell looks like a normal three-box sedan, and that’s a rear wiper. I reached out to Skoda UK to ask them about why they’re the solitary, brave voice of rear-visibility reason in the world, and got this response:
We do offer a rear wiper on some of our ‘sedans’, including the Rapid, Octavia and Superb – the latter being a free option on the vehicle. However, two things worth noting here;
1) The factory offer it as a free option on the Superb, not as standard, as the design department don’t like the look of it on the vehicle, as it ‘spoils’ the lines.
2) Although you might refer to our Superb, in particular, and to a lesser extent the Octavia and Rapid as sedans, they’re all full hatchbacks with a very gentle gradient for the rear screen. I can tell you from personal experience with the Superb, the angle is so shallow that water does gather/sit there and a rear wiper is very useful.
So, a few crucial points: first, I forgot that these Skodas used the very clever Twindoor system, where the cars have both a trunk and a fully opening rear hatch, depending on how you chose to open the rear. It’s really pretty brilliant.
The shape of the car is still very much a sedan, though, and that alone would seem to negate any shape/aero-type argument about why sedans lack rear wipers.
The most telling part, though, is what they said at first, and why the rear wiper is a ‘free option’ and not just standard; you have to request it. The reason seems to be in this statement:
That right there, I think that’s the fundamental reason why so few sedans have no rear wipers: because there really is no good reason. It’s all about design perception and old, lingering traditions that are incredibly firmly entrenched for no good reason.
For whatever reason, cars with opening backs are still somewhat second-class citizens in the automotive community. There’s some vestiges of old-school classism at work, I think, and the idea seems to be that a car with an opening rear is a car that works for a living, while a sedan, with a trunk, is somehow more genteel, and as such is above any vulgar outward displays of utility like an exposed wiper on the rear.
What else can explain why, for some reason, it’s just fine to have a wiper on a hatch and not okay on a sedan? There is no good reason, what we’re dealing with here is yet another irrational ‘rule’ of automobiles.
There’s no rational reason why hatchbacks or rear wipers should somehow be something to be ashamed of, or to have less strange, vague ‘status,’ but there it is. The thinking seems to be that lines of a sedan or coupé should not be sullied with some black waving arm on the rear glass, but it’s just fine for a hatchback.
It’s nonsensical, but there it is. If the automotive world was rational, you could just add a rear wiper option on almost any car, but the automotive world has never been rational, and never will be.
That’s both why I love it so and why sometimes I find it absolutely maddening. And I’m pretty sure that’s why there’s so many cars where I can’t see behind me in the rain.