eli5: How does the Eco/Normal/Sport mode on my car work?

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My new car has a dial to select Eco, Normal, or Sport mode. I can clearly feel the difference in acceleration when I change modes, and see the difference in the mpg, but I know nothing about engines and was wondering what the modes are actually doing. Camry Hyrbid if that matters.

In: Engineering

4 Answers

Anonymous 0 Comments

In modern cars, everything is controlled by the computer, including the throttle plate and transmission. So in Eco mode, what it will do is delay the opening of the throttle plate even when you floor the accelerator. It’ll sort of act like an “are you sure you want that much throttle” and then after X time passes it’ll be like “alright” and open it as far as you tell it. It will also be more aggressive with upshifting the transmission to keep the RPM lower.

Sport is basically the opposite. “Oh, you floored it? Okay let’s fucking go, man” and will open the throttle wide much faster. It will also downshift more readily and hold the current gear longer to keep RPMs high.

Normal is the middle ground.

Anonymous 0 Comments

Essentially the cars computer converts your input from the throttle pedal into actions on the engines. In sport mode it’ll deliver more throttle earlier on as you push your foot down, and that acceleration will be much steeper.

In eco mode, it’s a bit softer and will take longer to get to maximum throttle. 

This is all with the same physical input from your foot. 

Anonymous 0 Comments

They can do various things, but probably the main thing they do is change the shift points for the transmission. There isn’t an exact RPM or speed that shifting gears has to occur at, there’s a small range of them. “Sport” will usually wait until a high RPM is reached before shifting up , and “eco” will usually shift up at a lower RPM.

Anonymous 0 Comments

Your car’s engine is most efficient when the motor is run at low RPM and high load. However, this doesn’t deliver the most responsive performance, so automakers have take advantage of computer control systems to provide different “modes”.

In normal mode, the computer will balance efficiency and responsiveness to deliver a good balance.

In eco mode, the computer will cause the transmission to shift sooner, which keeps engine RPMs lower, but reduces responsiveness. The net effect is diminished performance, but better fuel economy.

In sport mode, the computer will cause the transmission to use lower gears, which increases engine RPM, but improves responsiveness. The net effect is better performance, but worse fuel economy.