As of 2013 there were a wide variety of propulsion systems available or potentially available for automobiles and other vehicles. Options included internal combustion engines fueled by petrol, diesel, propane, or natural gas; hybrid vehicles, plug-in hybrids, fuel cell vehicles fueled by hydrogen and all electric cars. Fueled vehicles seemed to have the short term advantage due to the limited range and high cost of batteries. Some options required construction of a network of fueling or charging stations. With no compelling advantage for any particular option car makers pursued parallel development tracks using a variety of options. Reducing the weight of vehicles was one strategy being employed.
The use of high-technology (such as electronic engine control units) in advanced designs resulting from substantial investments in development research by European and Japanese countries seemed to give an advantage to them over Chinese automakers and parts suppliers who, as of 2013, had low development budgets and lacked capacity to produce parts for high-tech engine and power train designs.
The chief characteristic of an automotive engine (compared to a stationary engine or a marine engine) is a high power-to-weight ratio. This is achieved by using a high rotational speed. However, automotive engines are sometimes modified for marine use, forming a marine automobile engine.
In the early years, steam engines and electric motors were tried, but with limited success. In the 20th century, the internal combustion (ic) engine became dominant. In 2015, the ic engine remains the most widely used but a resurgence of electricity seems likely because of increasing concern about ic engine exhaust gas emissions.
- Cardwell, Diane; Krauss, Clifford (April 22, 2013). "Trucking Industry Is Set to Expand Its Use of Natural Gas". The New York Times. Retrieved April 23, 2013.
- "Propulsion systems The great powertrain race Carmakers are hedging their bets on powering cars". The Economist (print ed.). April 20, 2013. Retrieved April 19, 2013.