HV-EV Button Question.

Sounds correct to me. I guess you will have to try it both ways and see which gets you the best results. Someone will lets us know if we are wrong.

 

makes sense to me. from everything we know about the non pip, regening electricity from the ice is less efficient than using it for driving. but i don't know if that's the case with li-on. it does seem less efficient to convert one type of energy into another and then use it because there are losses in all the processes.

 

Mid 50's for MPG on the highway make using the HV/EV button a no-brainer for me, since I routinely drive well beyond battery-capacity.

Saving electricity for when it can be better used is a nice option. The fact that the engine consumes electricity during warm-up to make it both cleaner and more efficient makes the replenishment of it later using gas is pretty much a wash.

Adding a plug to an already well thought out system is what gives Toyota the edge over competitors. Makes you wonder when everyone will figure out why that was such a sensible approach. And memories of naysayers claiming there was no advantage of the hybrid components while cruising on the highway are still so vivid. We'll never know if they didn't have a clue of what they were talking about or were just lying to impede progress.

Only now, as we start the second year and still only have rollout to 15 states, are we seeing some interest building. There's always first-year jitters anyway. Assumptions make it worse. There have been efforts to misrepresent too. Watching that change is reassuring... especially since we've seen other technologies stumble as time progresses.

Long story short (guess I climbed up on the soapbox there) is that you can't go wrong just giving it a try. Not pressing the button, you'll still get great MPG. Pressing it, there's a chance of squeezing out even higher overall efficiency.

 

This all makes sense for flat highway driving. If there are some hills involved (highway speeds or not) I use HV going up and EV going down. HV for the efficient Prius design using or charging the battery as appropriate. EV for mileage and possible battery charging.

 

That's how I see it as well. I think there is negligible difference in efficiency with either method until you account for what you do at the end of your trip and whether you can plug it in. If you can't plug it in and the distance is greater than EV range I almost always use HV mode. The logic is that there may be traffic returning home that I could take advantage of lower EV speeds. If there isn't then I use it up in boost mode.

 

Toyota knew we'd complain if we couldn't force EV mode on and off, so they gave us the button. But there's no need to use it; the car will do fine on its own.

 

Strategic use of the HV/EV button is a way to increase your actual EV miles.

 

I'm currently trying to figure this out myself.

My commute is 49 miles one way and both my home and work are within 1/4 mile of a freeway on ramp/off ramp. Posted speed limit is 65mph and 60mph is the slowest I can realistically drive without causing problems with other drivers.

So I can use EV for the short drive to the freeway then use HV mixed mode for some segment of my freeway drive then save a few EV miles for the last bit of the trip. The questions is, when do I use the freeway EV miles and do I drive just above the EV threshold so I can stay in mixed mode or do I drive at 61mph to stay in EV mode?

I have been driving at 65mph in the hopes that I am being ultimately more efficient in the use of EV energy, by mixing it with ICE, than trying to drive at relatively high speed just on EV power.

Once the weather stabilizes I guess I'll find out.

 

I too use HV for freeway driving and keep the EV miles for low speed local streets, where the trip is long enough to need both.

Is it more gas-efficient to (a) warm the ICE up in advance of getting on the freeway, (b) switch into HV when getting on the freeway, or (c) use EV to get up to speed and then switch to HV?

It seems to make sense to pre-warm the engine by going into HV momentarily a minute or so before getting on the freeway. But even though I switch back to EV, the MPG indicator seems to say that the car is running in HV, not idling the ICE and using the battery for propulsion. So maybe option (a) doesn't exist (unless you're sitting at a stop light)?

 

The way I understand it, no one is smart enough to know what method is most efficient. Just because it makes sense doesn't make it so. We empirically test it out and see for ourselves. I mean, it still makes no sense to me that the heavier PiP gets 1 mpg EPA highway better than a regular Prius. But there it is.

What makes sense to me is that b is most efficient unless the on ramp is a decline, then it's c. My reasoning is that your gas efficiency is lower when the engine is on. It makes sense the earlier you to turn on the engine, the longer it runs, and the more gas you use. You want to delay it until the last possible moment. But we won't know for sure until you test it for yourself.

 

In the interest of science I decided to let the car do it's own this this morning. I started off in EV mode as usual, hit the freeway and drove at 65mph for awhile then dropped to 60mph. I ended my 49mile trip (uphill) at 60mpg. That is pretty much what I get when I try to out think the system. My best was 61mpg and my worst when trying was 57mpg. So it almost seems like it doesn't matter. I did save 2.1 EV miles for the end of my trip when I hit city streets.

 

From everything I read, it seems like if you really want the ICE to contribute you need to give it a time buffer for it to warm up. Otherwise during that warm up time the EV will do all the work. I can imagine above 62 the ICE will be doing a lot more of the work however. Someone smarter than me can verify or shoot it down.

 

It's a balance. You use up more EV to aid warm up at high speeds than low speeds. But the ICE is more efficient at high speeds than at low speeds. Which one is more efficient? I'm sticking to using HV as soon as you have a straight shot to the freeway because obviously idling in HV nets you 0 mpg. If EV range exceeds the distances that you drive slow speeds, then you'll be using up EV on the freeway eventually anyway so no net loss.

The only way I can see a warm up for HV being more efficient is when you need to save EV at the end of your trip for slow driving. Most of my commutes are 90% fast speeds or 0% fast speeds. Basically, I use the freeway for most of my trip or I don't at all. So I rarely have to save EV.

 

How long does the warmup cycle in HV last? Same as a Gen3? If so that is only about 40-50 seconds if I remember correctly. Ideally you'd want to do a warmup cycle to be that amount of time when you are travelling 35ish mph or under but will be going higher directly afterwards....or stopping directly afterwards (such as before a light or stop sign right before an interstate interchange).

 

in summer, it's even shorter, but in winter, it can be a couple minutes.

 

There are time when I wish Toyota had put in a button and/or mode for a more aggressive longer lasting EV Boost when the ICE comes on. But then I get to where I'm going and am glad I have a little more EV to get through the city. I really didn't mind driving in the winter when the I hit the Auto climate button the engine comes on with a significant boost from the battery. The computer does get use your driving and adjusts accordingly.


iPad ? HD

 

Another EV/HV button question....

First, are you able to use cruise control while in EV. And second, if yes to the first, can you toggle between EV and HV without the cruise control kicking out?

 

I haven't seen any connection between the EV/HV button and the cruise control functionality.

 

Yes! You can use the cruise in EV.
I don't think I have ever even tryed to go from EV to HV with cruise control on, so I don't know about this. My best guess would be it would work, but I really don't know.