Question on EV/EV Auto buttons

I've tried all the modes in my 2 weeks plus with the car and have decided to just leave it in EV Auto mode. I'll let the computers decide the best utilization of resources.

 

I posted some general advice on this thread:
Mountain Driving Strategy | PriusChat

 

The short version is, “yes.” Broadly speaking, as you know from your previous Prii, the entire Prius line does a good job, on its own, of maximizing efficiency. Also, in the case of the P.Prime (and to a lesser degree, the original Plug-in) optimizing use of charged energy. It also gives you a lot of good hints on how to improve your driving style to improve efficiency, both in EV and HV operation.

However, there’s a couple exceptions, or at least “complications,” to that.

First, there’s that obnoxious warm-up cycle. A lot of the discussion on this topic is how to make the best of that like-it-or-not gas drain.

Second, and probably more importantly, there are cases where you, the human, can bring into the proverbial equation, information that the computer can’t possibly know. This, especially when you know for sure that you can’t drive your current trip entirely on EV. For example, if you know that your current trip is, say 60 miles, you can kick in HV mode only when HV will be the most efficient. Again, speaking in generalities, that’s during the sustained, higher-speed portions of your tip.

I’ll add, however, that, best I can tell at least, EV Auto mode is more for improving performance than for improving fuel economy. It mostly kicks in the engine to aid acceleration, which is one of those times when the engine is least efficient. I personally almost never use it, and think it would be more interesting if it kicked in the engine (again) during sustained higher-speed portions of your trip.

Still, if you charge when you can, and let the computer do the thinking about fuel/energy economy, you’ll do well! If you have time and interest to put into it, you may be able to do even better, but you’ll still do quite well without putting much thought into it.


iPhone ? Pro

 

"First, there’s that obnoxious warm-up cycle. A lot of the discussion on this topic is how to make the best of that like-it-or-not gas drain."

Haven.t seen those discussions, but a cold engine with cold oil is less efficient and has a lot more wear. A cold cat converter doesn't do it's job. The latest Prius warms up even more quickly using exhaust gas heat.

So the warm up cycle is there for very good reasons.

Best way to avoid it is to charge the car and use EV for short journeys. With the Prime, so long as you plug in, you never need to run ICE with its warm up cycle, for short journeys. Only for long ones where it becomes insignificant as a proportion of fuel use.

Posted via the PriusChat mobile app.

 

Given that you will subsequently run the engine for considerably longer than the duration of the warm-up cycle, then yes, I agree. However, I absolutely guarantee you that the engine turned off burns less fuel than a cold engine running!

If you need the engine for just a few-second burst of acceleration, say, the warm-up cycle is a big energy sink.

Ignoring the topic of emissions for now (that complicates and possibly changes the “equation”), I think it’s best to only run the engine when it’s power is needed, on a second-by-second basis. If the engine is needed, it will run and it will warm up.


iPhone ? Pro

 

Point taken.

However, in response:

1. Apart from when the EV battery was exhausted, my Euro car in EV mode has only started the ICE once in six months since new, and that was using adaptive cruise, going up a steepish hill and the car was also accelerating due to having just slowed down and then overtaken a slow vehicle, and crucially I think, it was not in ECO drive mode. So the car was accelerating much more harshly in cruise due to using Normal or Power drive mode.

2. I don't want to leave aside the issue of emissions, and Toyota designers don't seem to want to either. I certainly agree that they change the equation.

Posted via the PriusChat mobile app.

 

That’s a reasonable response, and all in all I personally don’t have too many concerns with how my Prius Prime handles the warm-up cycle.

Admittedly, that’s partly because I’m operating it 91% EV — probably 98ish% if I were to factor out the Austin->Houston->Austin road trip a while back (kinda a given that that would be on gas). Also, since they now heat-exchange the cooling water to the “cat,” the warm-up cycle is much faster than on our ol’ Gen-2.

What annoyed the crap out of me was when I would hop into our ol’ 2009 to drive a mile to the neighborhood grocery store, which, conceptually, I could get to with 3-4 kicks from the engine to get me up to 40MPH or so, followed by some engine-off EV operation. But noooooo! It would immediately hop into its (longer) warm-up cycle, which I would usually sit through to make sure at least some of that gas goes into the battery rather than all of it going to waste. It would then reluctantly turn off the engine long enough for me to back out of the driveway. As soon as I start to go forward though, it would kick in the engine, drive up to the stop sign at the end of the block, and take 10ish seconds to shut down the engine after I’ve come to a stop, when it should have shut off the engine the very second I took my foot off the gas leading up to the stop sign. After 3-4 cycles of that, the engine turning off for maybe 10% of that time, the engine is all warmed up, operating super-efficiently and ready for its 50MPG trip to ... oh wait, we’re already there! So I shut the @#$% engine off now that it burned a bunch of gas to get it all nicely warmed up for no useful reason!


iPad ? Pro

 

About EV Auto---
When I drive hilly roads on a distance greater than the battery can handle, the EV Auto runs the engine on steeper grades before the battery is depleted. I end up with less overall gasoline consumption for the total trip.

 

This video answered a lot of my questions!!!! Thanks!!!

 

Too many "modes" and too many "ECOs."

The EV Auto runs the engine when there is a higher load on the system. Drive in a hilly area with a charged battery and EV Auto, and on steeper sections the engine runs. This results in lower gasoline consumption overall on a run of a length where the battery will be depleted and part of the distance is on the engine.

EV is battery only until depletion, then the system automatically switches itself to HV.

The driving mode is merely accelerator sensitivity. In ECO, a moderate push of the pedal gets very moderate acceleration. In PWR you get a lot more zip for the same pedal travel. Normal is somewhere in between. Pick the setting that feels best to you for your driving and your traffic. There is no more total power available in any of the settings.

Does the HVAC ECO relate to drivetrain operation at all? I don't feel any change there.