By on January 18, 2018


ford f-150

Having previously discussed Day Light Opening (DLO), let’s define DLO FAIL.

And perhaps learn why DLOs sometimes fail?

Simply stated, DLO FAIL is when a design team’s Day Light Opening won’t make production, resulting in replacing glass with plastic “cheater” panels. Therefore, in internet-speak, the DLO truly FAILS.

DLO FAIL usually gives the appearance of a sleeker DLO without resorting to expensive glass. But that’s not the only mission.

The F-150 regular cab (above) implements DLO FAIL to integrate a single door design against multiple body configurations. It wasn’t implemented until the 12th-generation

The 11th-generation regular cab has glass in the B-pillar, except it’s actually a rear-hinged door. Great idea for truck buyers, right?


The designers went too far, making a regular cab more like a pricier super cab. Which goes against the grain of this machine’s mission as the value-packed workhorse, where frills are frowned upon by price-sensitive fleet buyers and thrifty consumers. Or beancounters looking out for the company’s bottom line. 1997 Ford F-150 Regular Cab, Image: Ford

The smarter route was the 10th-generation’s regular cab door, significantly different from the crew cab’s front door. Plenty of precedent, too: Ford turned the four-door 1990 Ford Explorer into the two-door 1993 Ford Ranger with this trick, albeit with more concealing effort. Trucks were predominately two-door before this: quad-door variants were usually limited-production, oddly crafted afterthoughts from the B-pillar back. 


But let’s not hammer only on the high volume, multi-cab configuration truck. Even buyers of a fully loaded ($154,000) Tesla Model X get DLO FAIL in the A-pillar as standard equipment. 

Tesla Model X Concept Car, Image: Tesla

The company’s concept SUV had a fantastic DLO; too bad even a niche builder gets it wrong sometimes.2006 Nissan Tiida Versa, Image: Nissan

So what’s the point? Remember there’s no excuse for DLO FAIL at either end. The Nissan Versa/Tiida or the Ford Fiesta prove that affordable models deserve real DLOs.

And if those are too expensive, perhaps the €5,900 Dacia/Renault Logan shows how not to FAIL on a budget.

Speaking of, what’s the budget to badge engineer the Mercedes GLA 250 into an Infiniti? Doing it with the brand-appropriate “E” shaped quarter window?

Compare the two side-by-side and Infiniti clearly spent some coin so the QX30 sported unique C-pillar skin and rear doors. But there’s no space for their stylized “E” quarter window, so they punted: opting for DLO FAIL.

What a shame, yet it proves there’s many reasons why DLO FAIL makes production. Even if none of them are especially palatable. 

[Images: Ford, Tesla, Nissan, and Sajeev Mehta]

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24 Comments on “Vellum Venom: What is DLO FAIL?...”

  • avatar

    One of the worst DLO fails today is the Miata RF. The car would look so much better if the panel behind the door was either body color or actual glass. I can’t un-see it on this car.

  • avatar

    How about ARTICLE FAIL?

    Not clearly written and pix are poor representatives of subject talked about.

    • 0 avatar

      I’d love to know what vehicles you’d prefer to see.

      • 0 avatar


        I’m only trying to extrapolate the feedback from the OP. I think if you had some more close up shops (Tesla Model 3 is the best example) and a bit more explanation it might help. I’m looking on a laptop, I can see it fine, on a phone those pictures are going to be really small.

        FWIW – keep up the great work – I wish you wrote more here!

  • avatar

    The first time that I heard this term was when written about by you guys regarding the new for 2014? Camry. Now each time I see one the phrase “DLO fail” goes through my head. Another offender that comes to mind is the Dodge Avenger which does not only have the piece of black plastic, but also some sort of supposed character lines running through it I suppose to make it look better for what it’s worth.

  • avatar

    Agreed on the DLO fail, it seems incomplete and unfinished. Related question, why do the “small” pick-ups have the small up-turn on the rear window (both crew cab configurations, and extended cab)?. I feel it raises the belt line too high in the rear and also “pinches” the look of the rear windows. Sajeev, what are your thoughts on this?

    • 0 avatar

      Interesting! I don’t see any correlation to the rear window (especially on the Taco) so maybe the turn up keeps the body side from being visually static. Or perhaps a better phrase is calling it over-styling because trucks are now lifestyle products.

      There could however be an engineering reason, as maybe the rear glass doesn’t roll all the way down and that upkick keeps the glass from being exposed when fully rolled down.

  • avatar
    30-mile fetch

    We have one of the more egregious examples of DLO fail sitting in our driveway. It isn’t a graceful solution to the conflict between intended design language and hardware limitations, but I don’t lose sleep over it. The DLO redeems itself with tall side glass and open visibility.

  • avatar

    Does anyone else miss operating vent windows? I can even recall operating vent window next to the c pillar on some cars in my youth. They were great for getting huge levels of fresh air into the car without the expensive air-conditioning systems that were only offered in the top end models. best of all when my Dad was chain smoking he would have the drivers vent cracked open even in the depth of winter and the smoke from his cig held in the left hand next to it kept his kids from suffering from secondhand smoke. perhaps when the outside giant rearview mirrors of today are replaced by tiny video cameras someone will bring them back?

    • 0 avatar
      Arthur Dailey

      And it gave you something to hold onto while you hung your arm on the window sill with the window down. Even better if you had rolled up the sleeves of your t-shirt and had a cigarette pack stuck into the sleeve.

  • avatar

    I had a Dodge Dart a few years ago that had a plastic triangle on the back door glass, it was obviously meant to be glass. I’ve purchased many, many Chrysler products over the years so I’m used to stuff like that, I know what I’m getting into as far as fails, panel gaps, and rattles.

  • avatar

    DLO fails are so “all over the place” I’ve stopped paying attention.

  • avatar

    The thing about the Jelly Bean 150 is that is wasn’t designed to be in a 4dr configuration, that was an after thought as consumers asked for 4 proper doors in the 1/2 ton instead of being forced into a 3/4 ton.

  • avatar

    I still don’t really get why these plastic filler panels are so offensive. Yes, they’re dishonest, but I reckon many designs are better for having them. On the single-cab F150 above, that black cheat panel gives the impression of a long, sleek DLO, and one that wouldn’t be production possible. I see no harm in that.

    Likewise, to go without the DLO fail, the Tesla would have needed either less headroom to permit that silhouette, or a more vertical windscreen to preserve the headroom. The door shutline couldn’t be taken any further forward, and the waistline couldn’t be raised, so there was nowhere else to go.

    I admit that I might be the worst car designer of all time – my career took me no further than graduation. But I reckon “DLO Fail” might be more charitably named “DLO We Tried”.

  • avatar

    Being aware of DLO fails since the concept was first written about in this site a few years back, I have to say I pictured Sajeev having some sort of visceral reaction to one of the biggest DLO fails, the 2016 Prius with its DLO fail applied to create that forked trailing and floating roofline at the back.

    DLO fail is more convincing in lighter colors. The dark contrast with the lighter color tricks the eye into blending the shiny black plastic into the glass area. Dark tint on the glass helps too. DLO fail is the worst on black cars.

  • avatar

    I think I may prefer the black triangle at the back of the rear door glass to the common alternative, no black triangle but the rear door glass is split into two panes, a larger one in front that rolls down (partially anyway) and a smaller one behind it that doesn’t open which often accounts for as much as 40% of the total rear door glass area. The latter arrangement adds an extra vertical divider which makes 6-window body styles like most hatchbacks look overly busy, and robs rear seat passengers of a decent-sized openable window.

    Most bothersome current DLO for me is the new Regal Sportback, which is designed to look like a 6-window body style but is actually a 4-window body with huge black fake windows in the C pillars. It’s almost as bad as late-period FWD A bodies (Cutlass Ciera, Century) which also had an unconvincing fake window in the C pillar, only larger.

    • 0 avatar

      “I think I may prefer the black triangle at the back of the rear door glass to the common alternative, no black triangle but the rear door glass is split into two panes”

      There’s no correlation between DLO FAIL and fixed vent windows on rear doors, as the FAIL is integrated into the roof and not the door. Last year’s Camry and countless other half-baked sedan/CUV designs prove that DLO FAIL is its own problem.

  • avatar

    DLO fail –

    A pet peeve of a failed car deisgner that writes for TTAC.

    That is all.

    In the real world, how many people would pay 20-100 bucks more for a car because it had an extra piece of glass vs plastic or paint? vs how many cars are sold?

    So what automaker is going to spend millions on something that people wont pay for, and wont affect the purcahse of cars?

  • avatar
    Mark Savino

    Love the DLO shit Sajeev!

    Would you call the C-pillar of current Renault Clio DLO-WIN? They bothered to add what I could only imagine is the smallest quarter window I’ve seen on any car… especially one at this end of the price spectrum.

    I vote for a future DLO-WIN post with some of the all-time best DLOs in the industry.

  • avatar

    I love this topic because I have a major hate-on for DLO fails. The previous generation Camry was the worst in recent memory. Previous generation Mazda6 wasn’t so great either. Miata RF… Acura ZDX (well that one’s just an overall fail). Would it be fair to include “floating roof” designs? I’m torn.

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