An easy way to determine if you are in "full hybrid" mode (also called stage 4), is to accelerate with the ICE past 20 miles per hour (don't exceed 34mph) and coast. If you are in full hybrid mode, the ICE will stop within 2 or 3 seconds of coasting.

Over 35mph you can't tell why the ICE stops - both stage 3 and 4 will stop the ICE when coasting above 35mph. Only if the TCH is in stage 4 (full hybrid) will the ICE stop if you start coasting under 35mph.

I discovered it is possible to go straight into stage 4 on restarting a warm engine. Power on the TCH and drive until about 30 seconds after the ICE starts. This time appears to be a "catalyst reheat" mode. After the ICE has been running roughly 30 seconds coast. The ICE will stop within a few seconds and you are in stage 4. Test by blipping the accelerator to restart the ICE and coast. The ICE should shut back off almost immediately. I've had this work at speeds under 30mph.

I don't know how long the TCH will allow dropping directly into stage 4 after restarting the TCH. I do know if I drive more than a few minutes it no longer will, requiring me to come to a complete stop for ~ 7 to 10 seconds to enter stage 4.

It's not meant to improve mileage (although it might in extreme cases) but it's there to prevent your mileage from tanking further than it would without it.

You make it sound like it's worthless. Try a car with the EV button then you'll see where and when you can use it.

You can engage EV Drive Mode before the engine starts so he can cruise the half mile street in the morning in EV Drive Mode. Then once he hits the main street, he can let the engine warm up.

Also, you can accelerate harder in EV Drive Mode than you can without it. Anything harder than a feather will engage the engine but in EV Drive Mode, it'll keep the engine off.

Mods: EV mod, VVT-i emblem, sport pedals, OEM cargo mat, JDM Prius interior footwell lighting, Sylvania Silverstars 9003ST, DICE iPod kit, OEM all-weather mats, TomTom ONE v2, LED licence plate lights.

Yup, well aware of this. But the bit I myself am still unsure of is how exactly it works for "warmed up and ready to go full hybrid". My impression at this point is.. maybe a mile of ground covered after it gets effectively warmed up? But the point where I can drop into full hybrid mode varies as it takes different amounts of time to get warm.... Some days timing seems perfect and I get to a red light after all green just about the minimum distance to go full-hybrid, and some days even pulling into a lot to stop for a few seconds to trigger full-hybrid--before I hit the interstate for about 2-3 miles then hit a stretch of low-speed no-stop road (where if I'm not already in full hybrid I can't trigger it)--it's still not ready. It'd be nice to have some more official insight (an indicator on the console?) to show that the car is sufficiently warmed up to get to stage 4....

What can I say, I want more feedback from my car sometimes.

I've gone straight to stage 4 without a warm engine. The car hadn't been driven since the day before but the block heater was plugged in.

Toyota may say that it won't improve mileage but I know that if I had it on my TCH I could get a slight improvement. The computer on the car is good but not as good as the human brain.

I suspect that what they are trying to convey is that it is not a panacea. You cannot stay in EV mode indefinitely.

I would like to see this feature migrate to the TCH but also to imrove on what they have used elsewhere. I can often get the TCH to go into EV at 35-38 miles per hour. It would be nice to have the switch and to have it function up to 40 miles per hour.

Yeah, I could definitely get a mileage improvement. On my street alone! Speed bumps prevent me from going over 25 mpg. Two trips everyday in EV mode would have a great effect. Too bad we don't get to use it.