Is it better to turn a car off or let run when trying save on gas?

It is generally more fuel-efficient to turn the car off rather than letting it run when trying to save gas. When the car is running, it is constantly consuming fuel, even if it is idling. For older vehicles, it can be more efficient to keep modern cars with advanced fuel-saving features like engine start-stop systems, which automatically turn the engine off when the car is idling and restart it when the driver presses the brake.

For older cars, idling for more than 10 seconds can use more gas than restarting the engine. However, modern cars with fuel-efficient engines and automatic engine stop-start systems may be able to idle for longer periods without wasting fuel.

As a general rule, it's best to turn off the engine if you expect to be stopped for more than a minute or two. If you're waiting in a long line or at a traffic light, it's better to turn off the engine and save fuel rather than letting it run.

Here are some additional tips for saving gas when driving:

- Accelerate and decelerate gradually.

- Drive at the speed limit.

- Avoid excessive idling.

- Keep your tires properly inflated.

- Get regular tune-ups and maintenance for your car.