With the term hybrid car it is meant a type of vehicle that uses two different types of propulsion. In general, hybrid cars feature an electrical engine as well as a combustion engine. Only the most desirable attributes of each engine type are utilized. When driving around town, with all the typical frequent starting and stopping that this implies, the environmental-friendly electrical engine gives the best performance, since it is quiet and releases no harmful polluting substances. On the other hand, when driving on the motorway, a hybrid car utilizes its petrol engine. The latter is capable of generating sufficient power to quickly propel the vehicle forward. When the battery power is low, the combustion engine starts working like a generator, and recharges the battery again.
In contrast to hybrid cars, bivalent vehicles possess a combustion engine, which is powered by two different fuel types. Examples of bivalent vehicles are natural gas-powered vehicles, and cars that are powered by Diesel and oil-based fuel (also known as biodiesel).
The combustion engine and the electrical engine in hybrid cars are thoroughly compatible with each other. The advantage of hybrid cars lies in the their ability for fuel consumption optimisation. As a matter of fact, fuel consumption is lowered by approximately 30%, thanks to the combination of both engine types. The Toyota Prius, which was introduced into the market for the first time in the year 2000, may be considered as the forerunner of composite engine vehicles in the automobile sector. Its fuel consumption is on average under 5 litres. According to its manufacturer Toyota, batteries last almost as long as the car’s own life, that is to say, 15 years. Nevertheless, in the case that the battery should prematurely run out, the replacement costs would become considerably high, with the car owner facing having to fork out well over 8,000 Dirhams. Hybrid vehicles do not necessarily require higher maintenance than normal cars, owing to the fact that technology has been increasingly perfected.
A significant disadvantage of hybrid cars is represented by their high acquisition cost, as, in contrast to conventional vehicles, they are considerably more expensive. Given the fact that they have two engines, these cars are significantly heavier than vehicles with a combustion engine. Therefore, when travelling on a motorway at constant speed, they do use up quite a bit more fuel than comparable Diesel vehicles. A hybrid car truly shows its strength when a lot of frequent starting-up and braking up is required. On the contrary, if the driver needs to travel longer distances at constant speed, or he (or she) does frequent motorway trips, a hybrid car will end up costing him extra because of the vehicle’s increased weight. A further disadvantage is represented by the narrow operating radius of a hybrid car. Currently, this ranges up to about 50 km in a purely electric mode.