Will the EV-Auto mode drain the battery all the way down if you drive far enough ?

Yep. EV/HV Auto in my experience is almost the same as EV only a little more aggressive in the use of HV for heavy acceleration. Both EV and EV/HV auto will deplete the EV portion of the traction battery. When that happens both will operate as in HV mode eg. act as a traditional Prius until the traction battery in charged via regen braking or downhill coasting.

 

As said above, EV Auto basically behaves like EV mode. It stays EV mode until the EV portion of the battery is depleted and then change to HV mode. EV Auto is useless mode for most people who drives conservatively. The only time the engine will kick in and change to HV is when you floor the pedal on quick and aggressive acceleration. My driving situation almost never calls for such aggressive acceleration.

 

Normally, EV on in-city stop and go traffic, and HV on highway speed works to be the most efficient. You can experiment with it to suit your driving preference and resulting mpg and miles/kWh. But just driving till EV runs out is the easiest way to drive and that's what my wife does. When I drive, I usually switch EV and HV manually depending on the driving distance and terrain. I try to use HV on acceleration and uphill, and save the EV on flat or downhill coasting. If the distance is substantially longer than the EV range (about 80 miles), you can get both good mpg and miles/kWh.

 

As my sig. says.

 

I personally don’t use EV Auto, but my understanding is that it’s basically the same as EV mode, except that it will sometimes kick in the ICE to reduce battery drain when you floor it.

Now the mode I wish it had could be sorta the opposite: Normal HV power management, except that puts an absolute lower limit on the moment-to-moment MPG, say 48ish. So, for example, if you “step on it” in normal HV mode, it guns up the engine RPM, and the MPG momentarily drops to zippo. In this hypothetical mode, it would instead burn down the battery for that added power, but still use gas for long, sustained power where the ICE can run at maximum efficiency.

 

My immediate suggestions would be:

First, if you have better things to think about, so to speak, just hop in and drive. The computer does a good job optimizing the drive system.

Second, if you know you can do your current trip on a single charge, then just keep it in EV mode.

Third, if you have a long trip, keep it in HV for long spans at highway speeds, and switch back to EV for driving through towns with stop and go traffic.

Fourth, again related to long road trips (necessarily) in HV, remember that it gets quite impressive mileage up to 55-60ish. I often see 60MPG, if I conditions allow me to keep my speed fairly consistent. However, mileage plummets rapidly above 60MPH, due to wind-resistance. At 75MPH, I rarely see much better than 48ish MPG.

With respect to Eco vs. Normal vs. Power modes, a few things:

First, in EV mode, this setting seems to be mostly just “throttle mapping,” meaning that EV Power mode mostly just interprets half throttle as a higher power setting than half-throttle in Eco. However, EV Eco mode also seems to automatically ease off the power a little after you get up to 30ish MPH.

Second, switching to Eco mode also automatically turns on Eco climate control. You control that explicitly too.

Third, Power vs. Normal vs. Eco doesn’t appear to be strictly throttle mapping in HV mode. In HV Power mode, it also seems to idle the engine more, ready for a jackrabbit start.

 

I myself do the vast majority of my driving in EV Eco, but no, I personally haven’t really seen much difference in range between Eco vs. Normal vs. Power mode, for EV driving.

Yeah, you definitely don’t want to drive much, if any, slower than the traffic around you. Heck, even 48MPG at 75MPH with the AC on is not bad!

 

The AC and heat pump are quite efficient, but they do cut in on range a bit. Not surprisingly, how much they do so depends upon how big a temperature difference you ask for. I generally, in hot weather, set it at 78ish, and find that it only loses a couple miles of range or thereabouts. All in all, I find that the heat pump is a little less efficient than the air conditioner, but not by much.

 

Indeed! If you cool it down to 72F, you probably won’t lose more than a further couple miles or so, assuming it’s rather hot outside. If your ‘Prime has the Remote-Climate feature, that can be helpful as well.

In colder weather, the steering wheel and seat heaters can go a long way too. I have found the steering wheel heater amazingly addictive , and that I don’t need to use the heat pump or seat heaters much.

Then again, I live in Austin TX, where three months out of the year, highs around 100F are pretty common, and lows in Winter only occasionally go below freezing. So, that’s the particular grain of salt to take my comments with!