Indian car maker Tata hopes to bring a car powered by compressed air — an idea that's been contemplated for years but has proved difficult to build commercially — to market. Built on technology licensed from Luxembourg's MDI, the AirPod is a light, apparently one-seated car that's supposed to be able to run at between 45 and 70 kilometers an hour (28 to 43 miles per hour). Instead of running on gas or electricity, however, the engine is powered by a tank of compressed air, which can either be pumped in through a charging station or taken in while driving with the help of an electric engine. The car can also recapture some energy during braking, similar to current hybrid vehicles. The concept still seems a bit shaky, but it could offer cheaper and more environmentally friendly recharging without waiting for something like IBM's lithium-air battery.

While MDI has been working on the technology for years, it signed a licensing agreement with Tata in early 2007, and a concept car was unveiled in late 2011. In May, the engine concept was successfully tested in two Tata cars, allowing Tata and MDI to proceed to the next phase: figuring out how to actually create a product that could go to market. We've heard nothing more so far, but it's meant to be developed "over the coming years."