What is the actual difference. In HV mode it uses the electric motors and the gas engine to manage the propulsion of the suv. In Auto EV/HV mode it uses the electric motors and the gas.

In the auto mode it will run EV until the battery is depleted and will run as HV. Auto mode is the default so you don't have to select it when you start the car up.

thanks, seems odd to have an actual 2nd button for it

My 450 doesn't default to Auto...I have it set to EV Only and that's where it starts.

Car defaults to EV mode when turned on. Press the HV/EV button, it will change to HV mode, which will run like 350h. Press the other button, you can change to Auto EV/HV which will use EV and the computer will use HV when it needs more power.

Interesting! The first question is, So if you have it in EV-only mode and you try to accelerate rapidly by pressing the gas pedal all the way down to the floorboard does it stay in EV mode, or does it add the ICE (HV)? And the second question if it stays in EV mode only what is the effective 0 to 60 acceleration time.

Thanks for your answers

YMMV,
MidCow3

In EV mode if I floor it, the ICE comes on. I'm really not sure what Auto is for, I've used it a few times, but can't tell the difference. I tend to switch between EV and HV based on what I know about my trip anyway, and doubt the car could do better.

In HV mode, particularly in Sport, I believe I'm using the EV motor too as I'm exhausting some charge during 'spirited' driving. I typically don't have the energy monitor up, just notice the EV range drop. Sport mode does make a bit of difference, haven't used Sport S much.

Since the ICE kicks in unexpectedly sometimes, if I'm planning any harder driving, I try to warm it up ahead of time.

Also, in EV mode, if my battery is full and I'm going downhill or when I'm heading down steep enough of a grade (regardless of battery level) and I brake hard enough or downshift the ICE also comes on. This has been fairly consistent. In some cases, it seems that the ICE is just on and idling for a bit but the EV motor is providing the main power as the RPMs don't vary with acceleration.

In EV, I would say the computer would try it's best to keep it in EV, so I would say it would stay in EV or rarely switch to HV under some circumstances. I have not been able to make the car turn on the ICE when in EV only mode, but I'm sure there are circumstances where it will. If you want that quick sudden fast acceleration, probably best to have it set to Auto EV/HV, -- in this mode, the car will kick on the ICE if you press the gas pedal down.

I don't have 0-60 time for EV, but I'm sure it is slower. But it does not feel slow because of the instant torque that you get on EV.

@ct6978 thank you for your excellent, clear answers, YMMV,
MidCow3

When I am on EV mode and floor it, the ICE does not come on for me. You sure you are on EV mode as the ICE shouldn't turn on in EV mode. In Auto EV/HV mode, it will turn on in certain situations and I have seen that when I'm on Auto EV/HV mode.
Only when the weather is extremely cold is when the ICE engine will turn on - even on EV mode.

Likewise as @lsft . When I'm in EV mode and I floor it the ICE doesn't come on. It only engages when exceeding 120KM/H.

It should be 135km/hr?

You're correct.

It has definitely happened for me going up a relatively steep grade, I remember being irritated by the car as I didn't think I was pushing too hard and the engine wasn't properly warmed up. I'll try to track when else it goes on. I have a memory or two of it going on on the flat, but I will try to confirm this. I switched my multi-function gauge to always show the tachometer even in EV mode, so it is obvious when the ICE comes on.