Question about feature with Transmission

[Richard]

Hi All,

I was reading some of the features of the Cruze and I saw one feature I don't understand. Maybe you can shead some light.

After you stop and your foot's on the brake for more than one second, the transmission shifts into neutral automatically - this is with the automatic transmission. Why would they have this feature? I find it quite dangerous. I noticed that the car was rolling back a bit if I'm on a slope and I take my foot off of the brake - almost like a manual transmission. Also, when I'm at a light, sometimes I will want to creep forward a bit and when I took my foot off of the brake, the car didn't move. Only when you hit the gas does the transmission shift back into gear. I didn't understand why it was doing this. Now I do.

What is the purpose of this potentially dangerous feature. Does the new Malibu do this also?

[michaelj3]

Fuel Economy!

[nutcrunch]

All I am familiar with is the 2013 malibu Eco.
It will turn off the engine automatically when you come to a stop at a light or whatever. As soon as you let off the brake the engine starts again automatically. When it does this it does not shift to neutral. This is done to save fuel when sitting still idling.
It also has HSA (Hill Start Assist) which is designed to prevent the car from rolling when you are on a steep hill and let your foot off the brake to put it on the accelerator.
Fom the manual...

During the transition period between when the driver releases the brake pedal and starts to accelerate to drive off on a grade, HSA holds the braking pressure to ensure that there is no rolling. The brakes will automatically release when the accelerator pedal is applied within the two‐second window. It will not activate if the vehicle is in a drive gear and facing downhill or if the vehicle is facing uphill and in R (Reverse).

I know the ECO is the only Malibu that shuts itself off at a stop and restarts itself automatically. Not sure if all the Malibus have HSA or if they shift into neutral at a light.
I don't really see how just going into neutral instead of being in drive at a stoplight with the engine still running would save that much gas.

[Richard]

Originally Posted by nutcrunch

All I am familiar with is the 2013 malibu Eco.
It will turn off the engine automatically when you come to a stop at a light or whatever. As soon as you let off the brake the engine starts again automatically. When it does this it does not shift to neutral. This is done to save fuel when sitting still idling.
It also has HSA (Hill Start Assist) which is designed to prevent the car from rolling when you are on a steep hill and let your foot off the brake to put it on the accelerator.
Fom the manual...


I know the ECO is the only Malibu that shuts itself off at a stop and restarts itself automatically. Not sure if all the Malibus have HSA or if they shift into neutral at a light.
I don't really see how just going into neutral instead of being in drive at a stoplight with the engine still running would save that much gas.

Right, the Malibu Hybrids in the previous generation did this also (the engine shut off at a light). But a car shifting into neutral can be dangerous. It's a good thing I read this on the Cruze Forum, because where I work, there are a lot of streets with slopes on them and I noticed that the car would drift backwards when I took my foot off of the brake. They should have at least made a feature when you take your foot off the brake, it goes back into gear.

I wasn't understanding why the car was rolling backwards when I took my foot off the brake until I read this on the Cruze Forum. And they even mention to be careful on streets with slopes because the car can roll when you take your foot off of the brake.

[Richard]

Originally Posted by michaelj3

Fuel Economy!

I thought that was the possible reason, but I can't understand how a car shifting into neutral at a light saves fuel. I was also thinking that it goes into neutral at a light to lighten the load on the engine. The generator efficiency is better in neutral than when it's in gear. Still, I would think it uses more fuel in nuetral. When a car is in Park or Neutral, the idle is slightly higher than when it's in gear. So I would think it uses more gas in Neutral. Personally, I don't even feel or hear any difference in engine speed when this happens. Still, if you're not aware of this feature, it can be dangerous. I have to drive it like a manual transmission. Go from the brake to the gas really quickly so the car doesn't roll on slopes.

[michaelj3]

At any constant RPM, the amount of fuel consumed by an internal combustion engine is proportional to the load on that engine.

An engine at min idle speed with no load must only deliver enough power to turn the flywheel and overcome friction of internal parts. Add a load to tha engine without increasing the fuel supply and the RPM's will go down. So, if you add a load and want to maintain RPMs, you have to increase the fuel supply.

If you find a way to idle an engine and maintain the speed on it regardless of how much load, PM me, we'll patent it and make a ton of $$$!

[MyMalibu13]

Sorry, but most of us come here to discuss and learn about the 2013 Malibu's. Better info on your Cruze might be found in the Cruze Forum.

[Richard]

Originally Posted by MyMalibu13

Sorry, but most of us come here to discuss and learn about the 2013 Malibu's. Better info on your Cruze might be found in the Cruze Forum.

Sorry, but I can't register on the Cruze Forum. There's some type of glitch with the registration process that they're looking into. Wasn't sure if the Malibu had the same feature with the tranny. I noticed that many of the electronics (DIC, My Link, etc.) are identical on the Cruze and Malibu, so that's why I'm posting here. Also, my last car was a Malibu.

When they fix the registration issue with the Cruze Forum, I won't post questions about my Cruze here anymore. I was just in contact with a representative that's trying to resolve the issue. Thank you to everyone who has been helpful with my questions.