Maybe, you are in S3a stage known among Prius drivers.
http://priuschat.com/forums/kb.php?mode=article&k=14
I've my TCH for only a month now and stumbled upon this forum, decided to read ALL threads from the first day onwards to make sure I get the "full" picture... Still working out the kinks w/ my User CP, so not sure how this msg will come out.

At any rate, I tried the link above and it's obviously dead by now. Can anyone guide me in the right direction? I've experienced the same issues Steve is talking about, and am *really* curious as to what I can do to bring my car back in EV mode w/o having to do a full stop. It happens even after I've driven for 40 minutes or so (at the end of my city commute, when getting close to home and 'cruising' down the neighborhood), so it's not about getting the engine warmed up again, for sure!

So what is S3a stage?

 

I've also experienced this. Sometimes I find if I give the engine a good rev (about 2 sec) it'll drop right into EV mode without coming to a stop.

 

I found this: http://www.john2211.nl/Hybride_modi.htm scroll down past the other language to get to an english description of the stages of operation.

 

I am curious too. It happens to me sometimes at the end of a 45 mionute drive. I would think the car would be warmed up by then. Can someone sum it up for us?

 

My limited experience in driving my wife's TCH is that after the car warms up and you are moving at or below 42 mph with no or very little acceleration for about 10 seconds the car will drop into the EV mode. Once in the EV mode, I can maintain it if I use gentle acceleration.

 

I have had the same problem. Seems just when you have it all figured out the car says HA I have a mind of my own. I am going to try to turn off the climate control and see if it has any effect.

 

I have found that the after some warming up the car can glide in EV mode alone with minimal pressure on the accelerator pedal but the slightest incline makes the gas engine come on.

 

Correct me if I'm wrong, but I think S3a stage is determined by the engine temperature. I've also made the similar observation recently after a couple of months of "feathering" the pedal. This week I find myself having difficulty shutting of the ICE when driving less than 40mph. I've never had this problem in the past while driving in the same LA traffic. Only difference I've noticed is the temperature here in LA has suddenly dropped into the 60's and low 70's this past week (as opposed to 90's and 100's just few weeks ago). I guess with the cooler weather, if I cruise around in EV mode too long the engine temperature will cool down and enter into S3a stage even if I've been on the road for over 30 min. Does this make sense?