Here’s one thing that often gets lost in the shuffle when debating the sexier points of green transportation: the simplest way to make a car, plane, whathaveyou more eco-friendly is just to make the whole damn thing lighter. All well and good, but how do you make sure that those industrial-grade plastic parts maintain their strength once you lighten them up? A technology developed at MIT called MuCell , and now being explored by automakers like Ford and Cadillac, has an answer. And that answer is: just add bubbles.

No, seriously: adding tiny bubbles of nitrogen or carbon gas into the normal injection-molding manufacturing process results in plastic that’s just as rough-and-tumble, but up to 10% lighter (according to estimates from Ford Motors, who’s very keen on using the technology). But wait: how does removing material from the part with these bubbles not make it weaker? The truth is that designers always massively “over-spec” the mechanical tolerances for these parts — usually 50-100%. So the relatively small reduction in material strength introduced by the bubbles is negligible, because the part was designed from the get-go to be much stronger than it’ll ever need to be in practice.

Ford hopes to use MuCell plastic in all its vehicles by 2020.

Still, that 10% weight reduction could help Ford meet its goals of eventually shaving off anywhere from 250 to 750 pounds from an average car. Ford is hoping to incorporate the MuCell-made plastic into all its vehicles by 2020. Luxury brands like Cadillac are circling, too. So why are they suddenly interested in MuCell’s microcellular foaming technology, which was actually invented nearly two decades ago at MIT before being commercialized by Trexel? Two simple words that matter now much more than they did in 1995: “Sustainability initiatives,” says Levi Kishbaugh, VP of Engineering at Trexel. “Automakers like Ford have sampled the MuCell process over the past decade and have achieved good results, and now they are taking the next steps toward widespread adoption.” Kishbaugh says that when MuCell is incorporated into part design and mechanical tolerances from the get-go (rather than applied downstream in the process), even greater weight reductions can be achieved while maintaining part strength: “20% or even more in many cases.”

Bonus: Not only does MuCell result in weight-optimized designs, it also uses less manufacturing material too. (Bubbles are mostly empty space, remember.) This isn’t to say that car manufacturers should give up on next-gen battery technology and other gee-whiz green engineering initiatives. But the small stuff — like zillions of microscopic nitrogen bubbles in a Ford manufacturing facility — matters, too.

[Top image, of soap bubbles, by Woodley Wonderworks]

[FC Top feat image, of Bubbles, by Thales]