EV to HV cut off speed

I'm a bit confused here. Many times I have gone as high as 65 mph in what I thought was still EV mode on a flat grade with gentle acceleration. I've been 70mph+ down a grade in EV mode with little to no accelerator input. In all of these cases, I saw no indication the ICE came on. Not only could I not hear or feel it, but there was no drop in instantaneously mpg displayed. Also, the EV mode display never changed to show another mode as it does when you run out of EV range. Every time I thought I could tell when the ICE kicks in, even if under very low demand and with electric assist, I always see a drop in instantaneous mpg displayed. Sometimes to 50-80mpg, but it's there. What am I missing?

 

When the ICE kicks in, HSI bar won't be divided in half (like HV mode). It will still have the full bar with EV icon on top missing. It is hard to miss and that's the EV-BOOST mode. Majority of the power will sill come from battery so the MPG may be above 100. The ICE starts very smoothly and I find it almost impossible to detect, especially at higher speed with some road noise.

All those things combined, it is very easy to miss and think the ICE didn't start. Amazingly refined and butter smooth how it blends.

 

I'll keep an eye on the EV icon next time, thanks.

 

Yup. Engineering is filled with tradeoffs. Seeing how high both the highway & city efficiency is for Prius in HV mode, it's clear Toyota found a balance that works well in real-world conditions. Finding out how well Ford's choice works out should be very interesting. The resulting numbers will tell us much and configuration choices.