You want to be on battery power as much as possible. All that the drive modes (ECO, LOW, etc) do is just adjust some parameters (gas pedal less responsive, aggressive regen) to make it a little easier for that to happen. Any mileage obtainable by using LOW or ECO is attainable in the NORMAL mode as well.
If you want the "LOW" mileage in normal you need to adjust your driving style between very conservative and spirited when the situation calls for it. The goal is to almost always be on at least partial battery power.
If you can, launch and accelerate reasonably under full electric power (downhill, 20-30mph road, nobody behind you).
If you can't do that (uphill, merging, etc) punch the accelerator... but don't floor it! You want to see half of your power meter be blue which is showing the electric motor doing at least 50% of the work. Once that blue bar starts fading you want to ease off the accelerator and ease back on to kick into full electric again.
Brake gently and try to avoid getting into the pads. Coast to a stop when reasonable.
This is my driving style and I'm getting a consistent 40-45MPG on an 11-mile 50/50 highway/city commute.
Only if it causes the driver to drive differently than the other modes might have them drive.
Must be a very specific driving area that allows it to be markedly better, or it's causing the driver to be very different.
Ditto to above - nothing different than can be accomplished anyway. (but I do like L in Ozark hills/turns, little braking needed then)
Except
In Eco mode - the AC level to reach setpoint is tamed down a bit - that uses less of the HV battery - that may allow you to be in EV longer when able to be.
In Eco mode - when Adaptive Cruise Control is getting back up to speed - it does it a tad calmer - that may allow you to be in EV mode a touch longer. If above 65 mph anyway - never mind.
In Eco mode - when you are below the set power limits for using EV (10 & 15%) and the ICE doesn't need to be used for HVB recharge or ICE warmup anymore - it can slip into EV mode quicker than the wait time Normal may give. But you can always release Go pedal and reapply carefully to do that anyway. That's when you see the blue outline bottom of white ICE bar.
What MY you in?
Pre-25MY doesn't get Ryom's indication of motor usage during hybrid time.
Also - you'll see bigger MPG gains by being thoughtful on your common routes.
Really only takes watching things once or twice to realize how you can basically coast or be in EV mode longer distance.
Thinking about where there are inclines followed by long levels or downs.
Don't waste the HVB going up and then require ICE on for the level and down distance.
Thinking about where you'll hit all lights red, or about to have some travel time.
Don't waste the HVB getting up to speed too slow, just to have nothing for next long distance you could be in EV mode. But if light to light, no need ICE coming on and running when coasting back down or stopped.
Super aggravating to have ICE running for HVB recharge at a red light, and ICE finally turns off just as light turns green.