Here’s the latest reader question, along with my reply!
Tyler asks: Are pop up headlights not around because of the ability for a car to absorb impact or because all cars must have day time running lights?
My reply: As Ed McMahon used to say – you are correct, sir!
Well, mostly!
While DRLs are not formally required in the United States, they have become de facto standard equipment in almost all new cars sold here. Because these cars are also sold in countries (such as Canada) where DRLs are required. It’s easier – cheaper – for a car company to build a one-size-fits-all car than to build a car with two different lighting systems.
DRLs are in my view among the most counterproductive of saaaaaaaaaaaaaaaaaafety features. Ostensibly intended to make cars more visible, they make motorcycles and emergency vehicles and funeral processions less so. They increase glare – and visual clutter. They also waste energy – as it takes energy (gasoline) to power the additional load of always-on headlights.
Pop ups are also complicated, failure-prone and expensive. The mechanism has to work reliably several times each day; over time, that wear and tear inevitably leads to wearing out.
Also, most if not all modern cars now have complex headlight assemblies rather than headlights. Pop-ups generally used standard sealed-beam headlights. They could be designed to use assemblies, of course – but the design ethic has changed because assemblies can be designed in almost any shape/style to give a car a certain look. The chief stylistic advantage of pop-ups – a unique look – has largely been co-opted by the unique appearance of today’s headlight assemblies.
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My biggest complaint about the always on lights is, it yellows the plastic covers faster than would happen if the lights were only on at night.
Hi Anonymous,
As a guy who rides motorcycles, I particularly dislike DRLs – which makes bikes (which used to be the only vehicle that regularly burned headlights in the daytime) more visible.
I think it’s more the sun that yellows the headlight lenses. Besides, you can get a restoration kit to clear up the lens again.
Mark, it’s definitely the heat of the bulbs that yellows the plastic. Scotty Kilmer has a video about it. LED lights burn cool enough not to cause this. I miss the glass jobs.. I have a newish car, and they’re already cheesed up!
Then explain to me how a Honda Helix scooter I got had a hazed speedo cover! By looking at the emergency kill switch (it was a dulled, flat red), I could tell it had been left outside for part of its life, which means it had received sun. Now, since the LED speedo display isn’t bright enough to do much damage, that only leaves one possibility for the hazing: sunlight.
BTW, the glass headlights were a lot easier to replace vs. the bulbs in the new plastic housings. The bulbs on newer cars are almost impossible to get to; they’re real PITA.
Anon,
I have a long time customer (I don’t really think of her as a customer, more like a Mom) that brings her 1999 VW Beetle in for regular service to my shop. She keeps her car in her garage and her headlights look brand new, So yea, the sun is what fucks up plastic headlights, not the bulb.
Retired PhD polymer engineer here, and I can tell you without question that it is the UV in sunlight that fogs plastic headlamps. The lamp assemblies are made from polycarbonate, which is tough and has a high impact strength but it is degraded rapidly by UV. Temporary protection against UV degradation is provided by a hardcoat on the face of the lens – it protects against scratches (polycarbonate is soft) and also absorbs the UV before it reaches the underlying polycarbonate. But the hardcoat eventually fails and is worn/flaked away, and then the lamp fogs rapidly. That’s why a new lamp will look good for years but a restored lamp – where the degraded surface layer is polished away – will start looking like crap in just a few months: the restored lamp has no hardcoat to protect it from UV.
Not all hardcoats are the same, and some last a lot longer than others. Most five-year-old Chrysler vehicles look like they are blind with cataracts, while most ten-year-old Toyotas and Hondas look bright and clear. I don’t know this for a fact, but I’m convinced it’s because Chrysler uses cheap crappy hardcoat to save a few pennies while Toyota/Honda/etc use the good stuff. Looking a used car in the “eyes” tells you instantly whether a manufacturer respects itself and its customers by building a quality product.
Excellent, Steve – thank you for this explanation!
That is exactly the case. Once upon a time I was responsible for PC parts with hard coat for a different but still optical application.
Scotty K proves himself a bigger moron every time I hear something he’s said.
It has nothing to do with heat and everything to do with UV.
At least Scotty Kilmer is ENTERTAINING! He’s fun to watch…
Heard it was also due to aerodynamic’s and drag coefficiency