A green car, also known as an eco car, is a road vehicle that produces less harmful effects on the environment than conventional cars. It is defined as a green car because it consumes less gas and therefore pollutes the environment less. A green car can run on electricity alone or a combination of electricity and hydrogen-based fuel, which means reduced carbon emissions. This means that carbon emissions into the environment will be at reduced levels and, therefore, the amount of pollution and emissions into the environment will be at minimized levels. Additionally, the ozone layer is protected and this helps protect all living things under the sun, including humans, plants and animals, from the sun's ultraviolet rays. Road transport is said to be the third largest source of carbon emissions in the air and if green cars are used, these emissions will be reduced thus creating a clean environment. Furthermore, green cars contribute to global warming as there will be no harmful emissions in the air that will cause climate change. Furthermore, the use of a green car offers the possibility of reducing dependence on foreign oil. This means that there will be no need to import oil as the dependence on oil will cease. Furthermore, the amount of oil discoveries has surpassed its peak 40 years ago and there is a possibility of an oil shortage in the coming days. With the use of green cars, there will be no need to prepare for oil shortages or build large oil industries as they run on electricity and other alternative sources besides fuel. Vehicle pollutants have been shown to pose risks to human health, such as lung cancer, respiratory and cardiopulmonary diseases. If eco-friendly cars were used, many lives could be saved. There are challenges within ecology. The central issue is to improve fuel economy by producing more eco-friendly cars on the market. Currently, four of their models are in operation and they are determined to develop a more complete range of eco-friendly cars. A good example is their Mohave fuel cell car, which has a maximum overall fuel system efficiency of 62% and the longest driving range. Saudi Arabia offers another solution with the Gaza 1, an electric car created by a student at King Saud University and which will be produced by 2016 based on a Mercedes G-class platform. The development of green cars is essential for national energy security and helps keep the environment clean of carbon emissions. Using a green car employs the use of clean renewable energy which produces less harmful emissions for the environment and having a high efficiency rate is a sufficient way to maintain a healthy and emission-free environment.