I recall asking this a few years ago here, but has anyone ever gotten the scoop on what Power Mode actually does? The owner's manual is absolutely useless, basically saying "push this button if you want to go faster". But I can't tell any difference other than the gas pedal getting more sensitive. At least in Eco Mode, they dial back the AC besides making the gas pedal less sensitive.

If I was designing it, I'd do something with the motor, like step up the max current applied, or deplete the battery further for a short period, so you actually accelerate faster even at full throttle.

 

I know in my prior CT200h that power mode placed the electronic motor or battery into overboost so it sucked more power out of the battery, and the engine management algorhythm is changed so the gas pedal feels more like a regular gas engine car with regards to responsiveness also the steering is tightened up. I expect all Toyota hybrids have similar features. According to Toyota the acceleration numbers are the same in normal or power, it just feels faster and responds quicker to less accelerator pedal pressure in power mode.

 

Your gas pedal is nothing more than a potentiometer. It's just a switch as there is no cable hooked to the carburetor like in the "olden" days. All Power Mode does is make the switch more sensitive so you don't have to move it that far.

I usually run in Eco Mode and the last few days have been really cold. I was chilled and my interior temp was set at 73. So I tested what the difference was between Eco and Normal Mode is.

When I pushed the Eco button, and the light went off, the engine RPM's instantly increased 1000, and the heater blower motor went higher. My heater immediately started blowing warmer air and the car got warmer. The gas pedal made it feel like I just put a 6 cylinder under the hood. I also watched my overall mileage drop at the stoplights because the engine ran on where it used to shut down before.

In the CT, it changed the color of the gauges, so it made a much more pronounced "feeling of power".

 

As much as it pains me to reopen a twelve-years-old thread, I think it is worthwhile to answer this question as to what the "ECO" and "PWR" modes really do. For future people searching.

This is the translated text from the Japanese Toyota service manual for the car. Take the choice of words with a grain of salt.

Driving mode
i. By selecting either POWER mode or ECO mode to suit the driver's preference, it is possible to change the hybrid system's output characteristics in response to accelerator pedal position.

ii. The riding modes are switched using the POWER MODE switch or ECO MODE switch located above the Shift lever. When no mode is selected, the vehicle is in Normal mode.

iii. To indicate the selected POWER mode and ECO mode, POWER MODE indicator lamps and ECO MODE indicator lamps have been set within the meter.

Normal mode
It optimally controls the ease of driving.

POWER mode
By controlling the driving force in the mid-range of the accelerator opening to a greater extent than usual, we aim to improve accelerator response.

ECO mode
By gently controlling the generation of driving force in response to accelerator pedal opening, increasing the airflow of the HV Battery Cooling blower, and setting the air conditioner to a fuel-efficient control setting, the vehicle can be driven with even better fuel economy.

and then there's a diagram of the accelerator pedal response in these modes:

So TLDR,

• when you use ECO mode and press the accelerator half-way down, it takes away some of that and only gives you, maybe 3/8ths of full power instead of half.
• when you use PWR mode and press the accelerator half-way down, it gives you more than you pressed, as if you'd already pressed it maybe 3/4 the way down. Meaning a little nudge on the pedal, and the car goes as if you were lead-footed.
• If you floor the pedal, you will get exactly the same response no matter what mode you'd selected. The main difference is that driving with a light foot will give you a squishy feeling car or a fidgety car.

 

Thanks for the cool graph! Yeah i've come to the conclusion that these power modes are mostly psychological. same with the "push to pass" button on german cars. If the car has an extra 20 HP to give you for 10 sec, why not just give it to you when you mash the throttle? Some make sense, like reducing the AC in eco mode, or if it changes the suspension to soften it up when you have the family, but the engine ones are just marketing gimmicks. Though the car companies know people want a button to push to make them feel more in control.