Prius Plug-in 2012-15 :: ICE Ignites When Braking Downhill

I've been mostly content with my Prius Plug-in for nearly a year now. But, as a driver very consciously aware of what my car is doing, I have many complaints concerning the internal combustion engine igniting when not needed, or remaining on for far too long. I do my best to work around them, but I feel the need to enumerate my complaints and vent about them. Note I live in southern California where cold weather is extremely rare, and I consciously don't use the heater or AC.

ICE ignites when braking downhill on a full charge. I've heard users say this is necessary because if the battery is full, regenerative braking will overcharge the battery.

ICE ignites if I step on the accelerator ever so slightly too hard. I understand that Toyota claims it needs to use ICE to deliver the extra power to the wheels asked for by the driver, but I just don't believe that. The engine usually simply idles and does not power the wheels at all when this happens, meanwhile the wheels are still running on 100% EV power. I know this because I've become in tune to exactly when the ICE powers the wheels and when it's not. The easiest sign of ICE actually powering wheels is when the accelerator begins to vibrate and I hear the ICE rev up. The second sign is by watching the MPG meter. If you're cruising at something like 50 MPH, and the ICE is idling, you'll see it getting about 80-90 MPG. When it actually supplies useful power, it suddenly drops down to 50 or below.

ICE ignites if the car moves faster than 65 MPH. This seems totally arbitrary to me. For example, it does not matter if you're accelerating steep downhill in neutral, or on a level highway just very slowly accelerating past 65. You can watch the power meter the whole time, and even if it doesn't get anywhere near the (power) section to the far right, the ICE still ignites as soon as you hit 66. In those situations, why does it even think it needs any extra power? And to top it all off, all it really does is idle for at least a minute anyway.

The ICE runs only momentarily, but here's the kicker: If you immediately let go of the accelerator, decelerate to below 65 MPH, or even come to a full stop at a red light, the ICE still continues to run for at least a minute or two. Worse still, it idles for about a minute regardless of speed or power, then suddenly decides that it should power the wheels for a few seconds even if no variables have changed, and it does this for about 30 seconds more before finally deciding to suddenly pop back into pure EV mode. How you work around all of this? Stop at a red light, shut off the car, and restart it. As it powers on, it stays in EV mode, proving to you that it never needed to be sitting there idling in the first place.