Automobile propulsion technologies under development include (i) petrol/electric and plus in hybrids (ii) Battery/electric vehicles (iii) Hydrogen cars (iv) bio fuels, and various alternative fuels. Alternative forms of power include the development of fuel cells, Homogeneous Charge Compression Ignition (HCCI), Steering engines, and even using the stored energy of compressed air or liquid nitrogen. New materials which may replace steel car bodies include duraluminium, fiberglass, carbon fiber, and carbon nano tubes. Telematics technology is allowing more and more people to share cars, on a pay as you go basis, through care share and car pool schemes.