eli5: how does the function of a car change when put into “econ” mode?


Im not quite sure if I worded this properly but basically I’m asking what changes in the car when we put it in econ mode? Like how is it that I waste less gas in econ mode when driving at the same speed as if I wasnt? Or how does the air conditioner work more efficiently?

In: 9

I believe it changes the gear ~~ratio~~ shift points, so your (automatic) car would have a higher threshold for gear changes, meaning you sacrifice power for fuel economy.

Throttle pedal is less sensitive and gearbox more hesitant to shift into a lower gear, amongst other things


Depends on the car but it basically reduces the effort needed by your car. It adjust the throttle, making you accelerate at a slower rate (cuts the horse power and torque). Its adjusts your AC so cooling the car takes longer. It adjusts the transmission by shifting at lower RPMs. But again the features change from car to car.

Dont use ECON if you’re towing, on super hot days you need AC and if you need to pass another car.

It depends on the vehicle. In some it will disable cylinders when at ‘cruise’ (that means little in the way of acceleration) meaning it uses less fuel that way.

In other ways it can change the shiftpoints if you have an automatic transmission, usually lifting it, to use more of the engine torqueband (which is when the engine is at its most efficient) rather than shifting for comfort or power.

Some engines will also lean out the mixture more, getting to the knock-point, and adjust timing to match, which also results in less torque. Some might also be more aggressive with engine braking, as that uses zero fuel.

There are other features that might be engaged, or made more aggressive, like engine stop/start, or variable valve timing. Or with fancy vehicles with adaptive aero, it’ll optimise for that.

In short, there’s a lot of things that can be done with modern engines, and what exactly is done depends entirely on the engine/vehicle itself.

My car has an econ button. Always wondered what it did because never noticed any difference. Turns out hitting it disables the stop/start, which doesn’t even work.

A gasoline engine is more powerful at high RPMs, but more fuel-efficient at lower RPMs.

So, typically, eco mode is all about making your transmission upshift later and downshift sooner.