what revs should a car idle at

[KhloeFitz]

A normal idle speed for most modern cars is between 600 and 1000 RPM (Revolutions Per Minute). While this is the general range, the exact ideal RPM depends heavily on whether the engine is cold or warm. A cold engine will idle higher, often between 1200 and 1500 RPM, to warm up quickly and run efficiently. Once at operating temperature, it should settle into a smooth, steady idle typically between 600 and 800 RPM.

Several factors influence where your car idles within this range. Engine temperature is the primary one, as explained. Engine load is another; if you turn on the air conditioning or powerful electrical components, the engine's computer (the ECU) will slightly increase RPM to compensate for the extra load and prevent stalling. The type of engine also matters. Smaller 4-cylinder engines often idle at the higher end of the range (closer to 750-900 RPM), while larger V8 engines can idle steadily at speeds as low as 550-650 RPM due to their greater inherent torque.

Vehicle Type / Condition	Typical Idle RPM Range	Notes
Modern Car (Warm Engine)	600 - 800 RPM	The most common standard for a stable idle.
Modern Car (Cold Start)	1200 - 1500 RPM	Higher RPM helps the engine reach operating temperature faster.
Performance Car	800 - 1000 RPM	Higher idle to maintain oil pressure and stabilize lumpy camshafts.
Large Displacement V8	550 - 700 RPM	High torque allows for a very low, smooth idle.
Diesel Engine	600 - 750 RPM	Generally idles lower than comparable gasoline engines.
Car with A/C On	+50 - 150 RPM	The ECU raises idle to handle the compressor load.

If your car's idle is consistently too high (over 1000 RPM when warm) or too low (causing shaking or stalling), it could indicate an issue. Common culprits include a vacuum leak, a dirty or failing idle air control valve, a faulty oxygen sensor, or a problem with the throttle body. A rough or fluctuating idle is a clear sign that your vehicle needs a professional diagnosis.

[DelGabrielle]

When you start the car on a cold morning, don't be alarmed if it revs up to around 1500 RPM. That's totally normal. It should calm down to a quiet hum between 600 and 800 RPM after a minute or two as the engine warms up. If it's still revving high after your drive or the needle is jumping around, that's your cue to get it checked out. Just listen to it—a smooth, steady idle is what you want.

[Karter]

Think of idle RPM as the engine's resting heartbeat. For a healthy car, it should be steady and consistent. In my experience, if the tometer shows a rock-solid 750 RPM when the engine is warm, everything is usually fine. The real warning sign is inconsistency. If the RPMs surge up and down on their own or the whole car shudders, it's often a sign of a vacuum leak or a sensor like the Mass Air Flow (MAF) sending incorrect data to the computer. That's not something to ignore.

[SanLeah]

I always notice the RPMs because I care about fuel efficiency. A high idle, especially when stopped at a light, means the engine is burning more gas than necessary. My hybrid idles so low it's almost silent, but my old sedan used to idle at nearly 1000 RPM, which hurt my gas mileage. Keeping your engine well-maintained—clean filters, proper spark plugs—helps ensure it idles at the most efficient speed, saving you money at the pump over time.

[DeCarter]

For me, the right idle is about how it feels. My truck has a big V8, and it idles with a deep, slow thump right around 600 RPM. It feels torquey and relaxed. My friend's tuned sports car idles at almost 1000 RPM; it sounds aggressive and ready to go. Both are "correct" for their design. The key is that neither should hunt or surge. If the rhythm is broken, something's wrong. It's less about a single perfect number and more about a smooth, predictable rhythm.