motor working at low speed

Your state of charge (SOC) could have been very low and the ICE was charging. Either that or your A/C temp was high and the ICE was trying to maintain the cab temp.

Welcome aboard by the way!

 

Also possible that the engine wasn't warm yet, depending on how far you had driven. It has to get to 70°C before it's fully warmed up, which can take quite a while in city driving, and even longer when it's cold. The engine will turn off when it's good and ready - and probably much faster in the summer than it does now.

 

If you have the heater running and it's cold outside, it is much harder to run on EV. I see a noticeable difference with the heater turned off in the cold weather. The ICE will run to keep itself above a certain tempo. If you are pulling heat out of the engine with the heater, it cools off faster than it would otherwise, thus causing the engine to run more often. You can turn off the heat, but you may freeze your a$$ off - you just have to decide how hard core you are

I have unfortunately had the opportunity to observe this first hand in the unusual cold weather we've had in the south. Brrrr...

 

This thread
http://priuschat.com/forums/gen-iii...-discussion/76501-gen3-warming-up-stages.html
should tell you more than you want to know about warming up the engine.

This info is derived by trial and error observations and is not complete or 100% correct.

Behavior you described sounds normal.

 

You don't mention the outside temp. but my experience is with the heater calling for heat, the engine (not motor, the motor is the electric thingy) will not shut down until the coolant gets above 63C. That takes 20-30 min. with full grill blocking when it's -10C outside. Even then, in traffic, it's hard to maintain engine temp. above that. So the engine will run to try to warm up so it can provide cabin heat. As my friend says, Pearl has a "gas heater".

You can easily test this. Turn off A/C auto and/or turn off the cabin heater. The engine should stop almost immediately if you are stopped, the coolant is above about 45C, and it has been about 1 min. since you last turned the car on (put it in "ready").

 

As long as you are running off the gasoline engine, the efficiency at 12 mph is atrocious. It's not surprising that you were able to get better fuel economy at 60 mph. I wide variety of cars get optimum steady speed fuel economy at some speed between 30mph and 50 mph. Efficiency is off the curve low at 12 mph.

 

The ICE has a mind of its own- its frustrating to be coasting downhill at 30 mph with the heat and ac off and a full battery, a warm engine, then have the stupid thing come on and burn 5-10 hp worth of gas for nothing. Happens to me all the time. All you can do is pull over and stop then it will shut off and behave normally for a while, as you continue to coast

 

+1! every nite i take the same route to work. i get off the highway and my battery is full green. it's 70 degrees outside ( a few months ago!) and no heat or a/c or even fan. no lites, no radio, nothing running but the car. i cut through the back of a mall and it's 20 mph max. no matter how gently i apply the gas, the engine keeps coming on. other times, with none of the above and the battery half blue, i can push pretty hard on the gas and get decent acceleration over a pretty good distance. 'the engine has a mind of it's own' should be our mantra!