The innovative Hybrid Air technology developed by PSA Peugeot Citroen is ready to go on sale - but will only do so when the company is convinced customers will adopt it.
The new powertrain technology uses compressed air instead of electricity to provide a secondary source of propulsion. When it was first revealed at the start of this year, PSA said it could potentially allow a car as big as a Citroen C3 or Peugeot 208 to emit just 69g/km CO2.
In a Hybrid Air vehicle, a conventional engine is mated to a bespoke epicyclic transmission, fed by a hydraulic motor which runs from compressed air. In the same way that hybrid electric cars can run on electric power alone for short durations, Hybrid Air vehicles can run on compressed air for a short amount of time.
However, speaking to Autocar at the Frankfurt motor show project leader Karim Makaddem said: "Creating the technology is not the hardest part. We have spent two years on the project, and believe we have found the solutions at an affordable price.
"But before we invest in production, we must prove that enough customers will buy it. Our market research must be rigorous - this is a very new product."