What is the difference between driving in EV mode via the button and driving in EV mode using HSI on the dash besides the higher speeds without the EV button used.
EV button allows a higher rate of acceleration in EV only. With enough charge, you can accelerate up to 25MPH, as long as you stay out of the PWR region of the HSI. When it hits 25MPH, the mode turns off. You will light off the ICE, if you keep accelerating. You can stay in Stealth non-button EV, if you lift off the accelerator pedal, and stay to the left of the middle point on the HSI. Stealth non-button EV will only allow you lay down enough power, to the left of the middle point on the HSI, but you can go as high as 46 MPH before it kicks you out.
Efficiency and battery life. Hybrid 101: - all energy comes from the engine burning gasoline. - heavy battery use is less efficient than light battery use Essentially the middle bar is where Toyota engineers think that on average using EV is less efficient than using the engine. At that point you almost certainly don't want to be in EV to maximize fuel economy. On top of that heavy draws from the battery will be more likely to shorten battery life.
Does anybody know of a way to allow the 25 MPH limit for EV mode regardless of the ICE temperature? It seems that I can never exceed 10 MPH in EV mode!