Air cars 2007–2016: CityCATs, AirPods and the production that never came

Between roughly 2007 and 2016, the air car was one of the most hopeful stories in transport. Prototypes with names like the CityCAT, the MiniCAT and the tiny AirPod were shown to the press, appeared at motor shows and featured in television segments around the world. Supporters, including the earlier website at this address, followed every announcement.

This is a look back at that decade from 2026, written without the hype and without the cynicism. The short version: no compressed-air car reached volume production, and the job the air car was supposed to do, cleaner and cheaper city driving, was taken over by battery electric cars.

The cast of vehicles

The cars came mostly from Motor Development International (MDI), the French company behind the compressed-air engine explained in our article on the active chamber. Over the years it showed a family of designs:

• Larger city cars in the CityCAT style, conventional-looking small cars with air tanks under the floor.
• The MiniCAT, a very small car meant for crowded cities, which became the focus of a development agreement with Tata Motors in India.
• The AirPod, a tiny bubble-shaped pod designed for short urban trips.
• Utility versions, from small vans to taxis, which appeared in brochures and plans.

The common thread was lightness. Because compressed air holds so little energy, every design had to be small, light and slow compared with a normal car.

The rhythm of announcements

Looking back, the decade had a recognisable pattern. A prototype would be shown, a production date would be given, and partners in different countries would announce plans to build or sell the cars locally. Then the date would slip.

Some landmarks from the public record, as summarised in the Wikipedia article on compressed-air cars:

• In 2004, production was predicted within months.
• In 2007, Tata Motors signed its agreement with MDI, and the air car became a global news story.
• In 2009, a Tata executive said cold engine temperatures were causing problems.
• In 2012, Tata announced progress to a second development phase.
• In 2017, first vehicles were said to be possible by 2020.

By the early 2020s, no air car had been sold in volume anywhere. Partner projects in several countries, including one in Switzerland, stalled or switched to other technologies. Some went on to build battery electric prototypes instead.

Why it stalled

There is no single villain in this story. Several hard problems added up.

Energy. A full tank of air at around 300 bar holds a small fraction of the energy of a battery pack of similar size, and a tiny fraction of the energy in a petrol tank. That limited range and speed, especially for anything bigger than a microcar.

Cold. Expanding air chills sharply, which robs the engine of power and can freeze moisture. It was one of the problems Tata reportedly ran into.

Refuelling. Filling 300-bar tanks quickly needs a powerful compressor at a station. Filling slowly from an on-board compressor at home takes hours and uses electricity, which raises an awkward question: why not put that electricity into a battery instead?

Safety and approval. Any new vehicle has to pass crash testing and road-safety rules. Very light cars with high-pressure tanks face extra work to meet them, and that work is expensive for a small manufacturer.

The competition moved faster. In 2007 lithium-ion cells were expensive and mostly found in laptops. By 2016 mass-produced electric cars were on sale, battery costs had fallen sharply, and the gap kept widening.

What replaced it: the electric car in the garage

The air car was right about some things. City driving is short trips at low speed. Most cars spend most of their time parked. Exhaust fumes in crowded streets are a real health problem. Those insights pointed the right way; they just pointed at batteries rather than air tanks.

In New Zealand, the shift has been noticeable. Electric and plug-in hybrid cars are a common sight, and most are charged at home overnight. The Ministry of Transport's environment and climate change work sets out why transport emissions matter so much here: with electricity mostly renewable, transport is one of the country's biggest remaining sources of energy-related emissions.

For a household, the practical questions are now about home charging: whether the switchboard can take it, what kind of charger to fit, and how to time charging for cheaper off-peak power. We'll be covering those in the transport section.

A fair way to remember the air car

It is easy to look back on the air-car decade and sneer. That would be unfair. The engineers and enthusiasts involved were trying to solve a real problem, and some of the thinking, about light vehicles, urban design and not burning fuel in city streets, was ahead of its time.

The fair lesson is about evidence. A technology is real when independent testers have measured it and ordinary buyers can purchase it, not when a launch date has been announced. Holding every emerging technology to that standard, including the ones we like, is the point of this site.

Read the companion piece, MDI's active chamber: how the compressed-air engine was meant to work, for the engineering, or visit the transport section for what came next.