AC comes on automatically when the heat is turned on. I questioned this long before and it's normal. Did you mean going from Eco to Power or Eco to Normal? I tested out Normal mode yesterday.
Maybe specifically on US car? I monitored AC compressor via ScanGauge for a protracted time, and: if the AC button was not pushed (light on button off), and the system was in Auto, the AC compressor never ran. OTOH, if I overrode, set Mode to Heat/Defog, then the AC compressor would sometimes run, dependent I think on a variety of conditions, ambient temp likely one of them.
AC operation should be the same in Normal and PWR. So, if some of the MPG change you saw when switching from ECO to Normal was due the AC difference between those modes, then that portion should not change again when switching from Normal to PWR. MPG changes due to factors other than AC should not follow the same pattern.
I've driven a whole tank in power mode. No difference in mileage vs normal mode. I found that in power mode I kept up with traffic off the line. For short trips less than 5 miles, normal mode had slightly better mpg while longer trips 5 to 8 miles got about the same. Trips over 10 miles goes to power mode. All trips are in the city with mostly city streets. Because I do short, mid and long trips, I averaged about the same for the tank in all 3 modes. Power mode gets better mpg if you do it with pulse and glide.
I mainly take short trips to work since I'm only 7-8 minutes away. At night and on the weekends is where I drive around alot. At 7k miles since brand new I average 48mpg in Eco mode. Do you mean to tell me my mpg's could be better in Power mode or not in my case?
I normally drive in normal mode, tried ECO mode a few times when I first got the car but didn't like it. Too lethargic. I find that Power Mode is best when driving fast in a hurry on the highway... Don't know about the MPG hit though.
Try a tank, in whatever mode your interested in. One thing: ECO requires such a long travel that at least for me, I found it harder to modulate. If that makes any sense.
Very true the way we all drive will yield different results, but I always thought of Power mode as a mode when I need to speed up quickly from a red light or to get on the highway. I never thought of it as a go to mode for 100% of my driving.
Well the thing is that PWR defaults to normal mode the next time you start the car. Only ECO and normal modes are retained when starting the car on the next trip.
Not going to argue with people that say they get the same or even better mileage with "Power Mode". Good for them. But... It seems to me in comparison to Normal and ECO...it's hard to believe that for MOST PEOPLE...you wouldn't take a mileage hit with Power Mode. Really, Toyota designed it for quick acceleration, for highway and freeway merges. It's primary difference is in a more aggressive mapping of the accelerator pedal. Less depression reaching more demand, thus mimicking quicker or a more "powerful" response. For most people, I think that dynamic IS going to result in less fuel efficiency. Just like the converse, which is ECO mode with a less aggressive mapping of the accelerator pedal is most often going to allow for most people to get better fuel efficiency. I use normal most of the time. And I do feel with years of Prius ownership now under my belt I can most often get nearly equal efficiency to ECO. Or that the difference is minimal enough that I most often prefer Normal. But I'm NOT going to use Power mode as my routine or default Full Time mode. I don't even think it was Toyota's intention of design, which is evident by the vehicle NOT staying in power mode once selected like ECO or even Normal. My feeling is Toyota intended Power Mode to be used for specific situations. Not full time use. And I bought a Hybrid Prius to be efficient....not necessarily "powerful".
I'll take you up on the fact that Normal mode works as good as or better than Eco. Let me try it on a full tank and I'll check back. Driving conditions, temps and driving style all affect mpg's. I wonder if I should wait until it warms up. We're still in the 40's here in WI.
Normal mode provides the happy balance for most drivers. That's the mode I drive in 98% of the time. It's good enough for merging and maintaining reasonable speeds on inclines. Don't think there is much of an MPG hit vs ECO mode. That's the mode Toyota had intended for end-users, but gave options to allow specific situations.
If you're coming from a gas guzzler and new to driving a Prius and less 1 year of owning a Prius, I can tell that you want to maximize the MPG. It's a new experience. I was like that too. Even with my V6 Tacoma which rated at 17city 21 hiway, I was able to get 21-22city with careful driving. After switching to my Prius, I tried everything to maximize MPG. I've driven in EV mode for over a mile depleting the HV battery (yeah, dont do that), driven in ECO mode for the first year. After a while, I started driving in normal mode and sometimes in power mode and drive more and more like I did with my Tacoma. Guess what, mileage didn't change all that much. Even now when I drive in normal mode, I can easily get over 600 miles to a tank with 17" rims sometimes over 700 miles to the tank. The way to achieve highest MPG is to travel the longest distance in 0 energy drain (gas or electric). The only way to do that is quick pulse and long glide. It doesn't matter what mode you do the quick pulse in as long as you get up to the speed as quick as possible without using much fuel. You can press the gas pedal 2/3 ways down in eco mode or 1/3 way down in power mode and get the same result. When you're in a Prius, your mind is trained not to press on the gas pedal down far. The gas pedal's spring up resistance slightly increases the further you press. Combining the two, driving in power mode is just more relaxing than driving in eco mode. Now, if you can accelerate at the same rate in eco mode as in power mode, then you're fine in eco mode and no need to switch to power mode. Keep this in mind too. The electric motor is assisting more under heavy acceleration (power mode) and less, most times none, in slower acceleration (eco mode.) The faster you drive, the more regen you get when braking adding back more electricity for your next acceleration. Once you get up the speed, you can glide further therefore maximize the distance traveled without using gas or electric.
Is it cold and snowy where you live? Keep in mind I'm in WI. 600-700 miles is almost impossible year round. I average 375 miles - 43mpg during the cold months and 475 miles - 52mpg during the warm months. So from what I'm hearing I should get out of Eco mode completely. What I feel I'm doing wrong is I'm taking my time to get to the speed limit. What mode are you in while driving the speed limit on streets vs highway? Do you ever alternate modes and why? What you said above is exactly right.