Is it bad to put the gear in neutral while car is running?

It's generally not bad to put a car in neutral while the engine is running *briefly*, for instance, when momentarily stopped at a light or dealing with a minor obstruction. However, it's not a good practice to do it for extended periods or habitually.

Here's why:

* Loss of engine braking: In neutral, the engine isn't connected to the wheels. This means you lose engine braking, making it harder to control the car's speed, especially on hills. You'll rely entirely on your brakes, which can lead to brake fade or even an accident.

* Increased wear on the starter: While not a significant issue for modern vehicles, repeatedly shifting in and out of neutral while the engine is running can put a small amount of extra stress on the starter motor, potentially reducing its lifespan.

* Possible damage in some automatic transmissions (rare): Some older automatic transmissions might experience slightly increased wear if frequently shifted to neutral while running, though this is uncommon in modern vehicles.

* Safety concerns: In some situations, quickly shifting from neutral to drive can result in a jerky start, potentially leading to a loss of control.

In short: It's fine for a very short period, but leaving your car in neutral with the engine running for extended periods is not recommended. Keeping the car in drive (or park, if stopped) is generally safer and better for your vehicle.