Engine on initially with EV mode, never get 199mpg

after how many seconds/minutes does the engine fire up?

 

You sure you’re in EV and not HV?

 

This:

causes this:

Because the battery is full when you leave and the car immediately has a long regen (charge) opportunity while going downhill but there is nowhere for that excess charge to go since the battery is full. So, the computers start and use the engine to burn off that excess charge.

There are workarounds for this but I'm not familiar enough with the choices available to the Prime to give you suggestions. For example, the Chevy Bolt EV has a setting in the charge menu to purposely not fully charge the battery so there will be an available buffer in the morning to absorb the regen charge while going downhill.

 

Do you have the defroster on? I think that starts the engine.

 

just to check, are you driving with shift lever in B mode?

I have inadvertently left in B mode after using to slow down on a long grade to a stop sign coming off a freeway, and this behavior sounds a lot like what happens when I did that.

 

What distance or type of hill are we talking about? I usually head downhill for a mile or so before hitting flat land and the car stays in EV mode the entire time. I'll even see more EV range than when I started due to the bit of regen I get going down the hill....

I ask because at some point a long enough hill might exceed what the car is willing to pump into the battery but for shorter hills do not seem to be a trigger.

 

Posted at 30-35 mph in 40F weather, I had one engine on even on the ascent and two on the descent. Stopping the car and power-cycle turns off the engine and reverts to EV mode.

Bob Wilson

 

Yes, the ice runs for a few minutes in the first fifteen minutes of use, nothing you can do, think of it as saving your electric range a bit.
I live at 1480' and everwhere I go is at 500' so yes my ice comes on even when going downhill, I prefer to use the ice when going up steep hills to save the traction battery for flats, going into winter I was averaging 97.3 but now I've slipped into the 80's, the ice won't turn off below 18 degrees, another unfortunate prius fact.

 

Interesting...Is altitude a factor in a Prime turning on the ICE?

 

If you don't charge to full at home, but only to perhaps 80% or so, you might be able to keep it off.

I've had the engine stay off for an entire trip down to 12°F.

No, change in altitude is. His problem is trying to regenerate into an already-full battery.

 

neutral and roll down the hill.

 

Why would the engine come on if the battery is full? I would think of it did, it would be like B mode where there's engine braking but not fuel is being burned.

 

Fuel is being burned during engine braking. Plus, if the engine hasn't been brought up to temperature previously, it has to burn fuel to run through the warmup process.

 

I see a similar thing...Leave my house, drive downhill about a mile...I usually burn a couple of tenths of a mile of EV range before I get to the steeper part of the hill, then recover and end-up about a half a mile of EV range over where I started.

I have not noticed the ICE starting...I keep the trip gauge set to "since last start" so if the ICE did come on and warm-up I would not be at 199.9 MPG at the bottom of the hill...

Maybe your hill is just steeper enough or just longer enough??? Clearly the battery has some extra room after a full charge because I can absorb more energy and see a larger EV range value...But I have no idea how much.

 

have you tried it without a full charge?

 

Source? This and other unofficial sites indicate otherwise Toyota Prius/Driving tricks - Wikibooks, open books for an open world

 

Knowledge of how engines work, observation of non-infinite MPG during engine braking on many cars, and the fact that warmup has to happen if it hasn't happened already.

 

Pure B mode with the foot off the gas cuts off the fuel flow, from what I've found in internet searches. Makes perfectly logical sense to me as why waste fuel during engine braking when it isn't needed? Yeah, probably triggers a warm up cycle though.

Fuel is cut off on gassers too during deceleration GM says deceleration fuel cutoff in Cruze increases fuel economy by up to 2% - Green Car Congress