<Table> <Tr> <Td> </Td> <Td> This article relies largely or entirely on a single source . Relevant discussion may be found on the talk page . Please help improve this article by introducing citations to additional sources . (May 2012) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This article relies largely or entirely on a single source . Relevant discussion may be found on the talk page . Please help improve this article by introducing citations to additional sources . (May 2012) </Td> </Tr> <P> Overdrive is a term used to describe the operation of an automobile cruising at sustained speed with reduced engine revolutions per minute (RPM), leading to better fuel consumption, lower noise, and lower wear . Use of the term is confused, as it is applied to several different, but related, meanings . </P> <P> The most fundamental meaning is that of an overall gear ratio between engine and wheels, such that the car is over-geared, and cannot reach its potential top speed, i.e. the car could travel faster if it were in a lower gear, with the engine turning at higher RPM . </P>

What is the purpose of overdrive in a car
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