Should You Put Your Car In “P”, “N”, or “D” Mode While Stopped at a Traffic Light?

It’s odd that we debate this at all, but what mode you put your car in while idling is a hot topic. Some say putting your car in Drive mode will wear on your brakes. So which gear shift mode should you use?

First of all, let’s understand what happens when you shift the gear of your Automatic transmission into these modes:

• “P” – Park
• “N” – Neutral
• “D” – Drive
• “R” – Reverse

There’s also the fancy “S” for sport mode, i.e., a mode that keeps the RPM up and maintains a higher rev for you to get through hilly terrains, or when you’re feeling a need for speed.

Then there’s “B” for Brake Gear or “L” for Low which helps during descending steep hills. It engages lower gears that helps slow down your car.

What Does It Mean to Put an Automatic Car Into Park “P”?

Mechanically, the transmission parking pawl — a metal pin within your transmission system — will move into place, locking the transmission in place and preventing the output shaft from rotating. As long as the output shaft is not rotating, the road wheels can’t move.

So, when you put the car into Park, you are doing so because you are getting out of the car and you don’t want the car to move at all from wherever you’ve parked it. It’s the way to properly secure your car in place when you’ve stopped, as opposed to putting it in Neutral “N” which does not do that.

Even though the transmission parking pawl prevents the output shaft from rotating, you should still apply your parking brake, be it mechanical or electronic. This is to prevent any failures of the pawl.

What Mode should you put your car in while stopped at a traffic light?

When you stop at traffic lights, the best and most efficient thing to do is simply use your foot brake to slow yourself down and come to a stop, and then just hold the foot brake in place.

You might think this would cause wear and tear on the brakes, but actually it won’t. Provided you steadily brake to come to a stop, it won’t do your brakes any harm to hold them while stopped (especially on a flat road) because there’s no heat being generated, and very, very little being generated when you brake during “creep” mode.

Should you put the car in Neutral while idling?

Some people online have argued that in Drive mode with the brakes on, the torque converter heats up as it is still engaged.

It’s actually less harmful to keep the transmission in Drive because all that shifting in and out at stop lights can just wear out the transmission more. Especially the shifter linkage and manual valve in the valve body.

There’s no reason for you to ever shift it in Neutral while sitting at a light. The torque converter doesn’t heat up while sitting at a light anymore than it heats up in normal use of driving. It’s not like being in Neutral disengages the torque converter, it still spins and still gets hot.

Automatic transmissions are more sophisticated and have been built to function without the constant shifting between drive modes.

That said, keep the car in Neutral while it’s being towed. If an automatic car is being towed, you mustn’t leave it in Park as this will cause serious damage to the powertrain and drivetrain units.