Vellum Venom: What is DLO FAIL?

Sajeev Mehta
by Sajeev Mehta

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.

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.

The company’s concept SUV had a fantastic DLO; too bad even a niche builder gets it wrong sometimes.

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]

Sajeev Mehta
Sajeev Mehta

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