Indian carmaker Tata Motors is voicing concerns about the range and durability of the compressed-air powered minicar technology that I critically analyzed for IEEE Spectrum this month (see “Deflating the Air Car”). Tata Motors invested in French air car developer Motor Development International (MDI) in early 2007, but yesterday Mumbai-based news source DNA reported that Tata sees ongoing issues with MDI’s technology.

Tata already sells vehicles that run on gasoline, compressed natural gas, and liquid petroleum gas and is launching a battery-powered sedan in Europe. However, Tata Motors’ vice-president for engineering systems S Ravishankar apparently told DNA Money that the company’s efforts to add air-powered cars to its fleet are hung up by range limitations:

“Air is not a fuel, it is just an energy carrier. So a tank full of air does not have the same energy as a tank full of CNG. Any vehicle using only compressed air to run would face problems of range.”

When asked whether this means that “the ‘Air Car’ project [is] off?,” Ravishankar declined to comment. Instead, Ravishankar added that excessive cooling of the air car’s pneumatic engine is also presenting a challenge.

Spectrum‘s analysis of the thermodynamics of MDI’s AirPod concluded that the minicar is not energy efficient relative to electric vehicles, and unlikely to deliver on its promised 200-kilometer-plus range. New York Times auto columnist Jim Motavalli poured further cold water on pneumatic propulsion last week, reporting on a UC Berkeley report on the poor efficiency of pneumatic vehicles.

MDI, for its part, continues to talk up the AirPod’s imminent commercialization, and has forged what may be the firm’s first university partnership since an unsatisfying collaboration with France’s prestigious École des Mines de Paris (which deflated ambitious range claims for an early version of MDI’s technology). Switzerland’s ArcInfo reports this week that an MDI partner in Reconvilier will commence manufacturing of the AirPod “from March” and the École Polytechnique Fédérale de Lausanne will fund a doctoral student to help boost the efficiency of MDI’s air compressor stations.

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This post was created for Energywise, IEEE Spectrum’s blog on green power, cars and climate