Whats better for fuel economy?

I would let the vehicle warm up...Once the ICE turns off which is usually a minute or less this should place the system in S2 .

 

Depends on your commute, and if you have an EV switch.

For instance, my first couple miles is me going down a gigantic mountain @ speeds under 35mph. Therefore, I start and go. Once 51 or so seconds has elapsed, I press the EV button which shuts the ICE off and takes it out of S1 for good. When I get to the bottom with a fully charged battery and a warmed up but off engine, it is nice.

But everybody's trip is different.

 

Your MPG while sitting there warming up is "0". I would just go

 

There's been a fair bit of debate over this issue in the past and I think the conventual wisdom is to just drive it without warm up.

Personally however I think there are circumstances where it's worthwhile to allow a short warm up. I notice then when I drive immediately from cold that the car very much attempts to use the traction battery in preference to the ICE for the first minute or so. Sometimes this results in the battery dropping several bars of SOC very quickly and of course that can mean reduced MPG's for the next several minutes or more.

So if I have the option to just drive very slowly, without any hill climbing and without dropping much SOC for the first 40 sec to 1 minute then I think it's good to let it warm-up while driving. If on the other hand I've got to drive a bit harder in the first minute and it's likely to start dropping SOC as a result, then I think it's both easier on the car and no worse for FE to let it warm for 30 or 40 seconds before taking off.

 

Uart's answer is correct. I won't bother restating it.

Tom

 

Using EV is generally bad for your mileage. Make sure you understand why before making a habit of using it.

Tom

 

When the car is already in warmup mode, and less than 50-something seconds have elapsed since the engine turned on, there is no way out of it short of restarting.

However, once the time period has elapsed, or you drive above 55kph then you can get into the regular driving modes as well as EV.

Definately agree. EV is cool, but you really have to know when and when not to use it to optimize fuel economy. However, it is damn nifty to creep around parking lots scaring the bejeebus out of people when a silent car goes by...

 

There is a way to engage EV mode (via factory EV button) when the car is cold, but as has been said, it's generally not a good idea to do so. For normal driving the sooner you get past the warm-up phase the better, so it's not helpful to delay it with EV mode.

That said, all you have to do to get EV mode at cold start is to make sure you hit the EV button before you engage gear. That is, get the car to ready mode as normal then while it is still in park press the EV button. This is really useful if you're just moving the car a short distance, say from one parking space to another, or in and out of the garage for cleaning etc.

 

Actually, the EV button needs to be activated within the first few seconds, regardless of gear.

To the OP, the EV button may improve fuel economy if used properly and the right conditions exist. As you seem to realize, it should not routinely be used for propulsion, but it can be used to force ICE shutdown during later warmup stages when propulsion is not needed. See this for more.

 

I believe ken1784 would disagree. If I remember correctly, he did tests and showed that it was more efficient to just let it warm up than to put a load on the engine and start driving it. I believe he actually had it warm up in N, which used even less gas than P. And I guess the loss of the small amount of battery recharge in N vs. P was still in favor of N. (But of course, if you leave it in N it will run all day, you must shift at some point.)

 

Those words are not from mine.

Everyone's situation are different, therefore YMMV.
During the first 1 minutes of S1a warming up cycle, the ICE does not produce motive power, then Prius uses battery power to drive it.

If your road is downhill for the first 1 minute, you can start immediately after READY on.
If your road is uphill for the first 1 minutes, wait for 1 minute to finish the S1a stage, then go.
If your road is flat, it's your decision. You can start immediately and drive slowly to save battery power, OR you can wait for 1 minutes then start your driving at normal speed.

I don't recommend to do the N range warming up.
We saw less fuel usage in N than P, but it takes longer to finish complete warming up, therefore we saw almost same total fuel usage for complete warming up.

Ken@Japan

 

Has anyone did an AC on with fan low speed check versus windows partially down.

 

This is exactly my approach. I used to rent a room from a woman who lived at the bottom of a long steep driveway. There, I would sit and let it get into S2 before moving.

Now at my house, level terrain and light traffic allow me to move under low power for the first 2-3 hundred yards (all it takes to get through S1 after a block heater preheat), so I move out immediately.

 

See : http://techno-fandom.org/~hobbit/cars/five-stages.txt

 

It depends on climate.
In a hot weather, it takes less than 5 minutes or a few miles drive to reach S3.
In a cold weather and heavy use of cabin heater, the engine coolant will never been reached above 163F and Prius will stay at S2.

Ken@Japan