Most modern consumer vehicle engines are pre-programmed with specific fuel-to-air ratios, so introducing water without re-programming the car's computer or otherwise changing these ratios will most likely provide no benefit, and may likely reduce performance or damage the engine. In addition, most modern fuel systems cannot determine that water in any form has been added, and cannot determine a new compression ratio or otherwise take advantage of lower cylinder temperatures. In most cases in pre-programed cars, introducing water vapor via an indirect water injection method causes loss of power because the water vapor takes the place of air (and fuel in engines with either a carburetor or single point injection) that is required to complete the combustion process and produce power.