Engine speeds for cars with automatic transmission are usually in the following ranges:
* Ideal speed (idling): 500-900 rpm
* Acceleration speed: 1500-3500 rpm
* Speed while maintaining constant speed: 1200-2500 rpm
* Overtaking speed: 3000-4500 rpm
The exact engine speed for a particular vehicle may vary depending on:
* Engine type and characteristics
* Transmission ratios
* Vehicle size and weight
* Driving conditions (speed, inclines, load)
Typically, engine speed increases slightly when the transmission is put into drive or reverse. This is because the transmission puts stress on the engine.
For optimal performance and economy, it is recommended to keep the engine speed within the recommended range. RPMs that are too high or too low can result in increased fuel consumption, reduced engine life, and transmission problems.