Shattering Glass: Low-Weight Plastic Car Windows are Coming

Detroit has one word for your windshield: Plastics.

Well, polycarbonate glazing, to be specific. It isn’t new, but despite added cost it’s a concept made for these times. It can be easily molded into all kinds of shapes, and it offersa 50 percent weight savingsas fuel economy-conscious automakers look wherever they can to shave a few ounces off a car’s bottom-line weight.

Two companies are competing head-to-head on polycarbonate car windows, Bayer MaterialScience and Sabic Innovative Plastics. Sabic spokesman Venkatakrish Umanaheswaran told Ward’s Auto that an Indian or Chinese carmaker may be the first to outfit a car with all-plastic windows because the expanding industries there are designing vehicles with a clean sheet of paper. Sabic expects to see a breakthrough vehicle on the market around 2015.

Saving money down the road

Polycarbonate is more expensive, but if it’s incorporated into an all-new design it can ultimately save money by allowing the molding in of what are usually extra-cost items like hatchback lift handles and wiper blade bases. A roof spoiler can also include a third brake light.

Sabic, a Saudi company that acquired the former GE Plastics, is investing in its hunch — it’s building a large-scale polycarbonate facility with joint-venture partner China Petroleum & Chemical, to open in 2015.

Bayer (yes, the same German company that makes aspirin) has made experimental plastic-bodied cars since 1967, and recently announced it was building a battery-powered plastic supercar. It makes the roof panel on current Smart cars. Bayer is also blending polycarbonate with used PET pop bottles to create a new body panel material that could become a spoiler or trunk lid.

Safety first

Another reason that polycarbonate windows may appear first in the developing world is less-stringent safety regulations. NHTSA and other agencies will have to be convinced that plastic windshields and rear windows won’t increase accident fatalities. Such applications, of course, have long had a place in off-road vehicles and in racing. The high-performance Porsche 911 GT3 RS 4.0 uses ultra-light polycarbonate quarter and back windows in Europe, but those plastic parts were nixed by federal regulators in the U.S. version. You can, however, buy aftermarket polycarbonate windowsto lighten (and speed up) any and all Porsche 911s.

But polycarbonate is sneaking into the western auto industry as glass replacements in non-strategic areas. Hyundai has used it on concept cars, and Bugatti on a new lightweight targa top for the Veyron (saving 13 pounds). The most prominent mainstream users of polycarbonate right now are Mercedes (which puts it into fixedSmart side windows, as well as those roof panels) and Toyota,which is introducing it on the V, the new station wagon version of the Prius.

Let there be light

Toyota went through an extensive lightening exercise on the V, due this fall, because the goal was to make a larger vehicle without losing much on the standard Prius’ combined 50 mpg on the highway. So the V gets an optional two-panel panoramic plastic moonroof that is half the weight of a theoretical glass version.

Glass sunroofs are really heavy, so Toyota’s happy to keep the V to only a 232-pound weight gain (and 42 mpg combined). Another advantage, Toyota spokeswoman Jana Hartline told me, is that plastic polycarbonate sunroofs can be engineered to absorb infrared light and reduce the need for both cooling in summer and heating in winter.

Both Sabic and Bayer say they’re seeing a huge increase in requests for polycarbonate parts, although still mostly for lightweight prototype cars (like that Hyundai HED-4). Their dream is to replace glass on cars entirely, and they’re settling in for the long haul.