Will the Prius Prime use gas even if in EV mode?

From what I have read the prius prime motor will go on periodically to just check all systems are working even if you use EV all the time. It warms the engine up, checks all systems, fluids and shuts down as a diagnostic test. Its a brilliantly engineered car designed for the utmost efficiency and reliability.

 

May I ask where you read this? I don’t remember seeing it in the manual, but I haven’t read the whole thing.

 

In EV mode if you step on the accelerator pedal hard it will switch to hybrid mode and use some gas, the EV symbol switches to just an outline of the car icon. It happens to me sometimes if I need to pull out into traffic quickly. But if I am careful to gradually speed up it stays in EV mode.

 

Just a few weeks ago my engine kicked in out of the blue and I was not sure if I caused it or not I was sure not but who knows. I still had 10km/6.2mi of electric to go. At the next red light I restarted the car to turn off the ice and carried on my way in electric.

 

Indeed. The original PiP (plug-in Prius) did this, but not the Prime. The PiP did that (largely) because it didn’t have the Prime’s sprague clutch on the engine, which allows both motors to generate torque.

I hardly ever use EV-Auto mode (come to think of it, I can’t recall ever using it in over three years), but I gather that mode behaves like the PiP.

Best I can tell, the thinking behind EV-Auto is to mostly drive EV, but to kick in the ICE to assist the motors when you do something that would otherwise drain the battery quickly. Then again, I’ve heard that EV Auto mode hardly ever seems to kick in the engine.

As I’ve mentioned before here, I’d have preferred a mode kinda-sorta opposite of EV Auto: Same as hybrid mode, but with an absolute-maximum limit on instantaneous MPG. So, if you step on the gas, which would typically suck up a boatload of gas, instead drain the battery for that, and only kick in hybrid mode to sustain long-range cruising.

 

You're correct if @Dave7 is in Connecticut, but not if he is in Catania. European Prius PHVs don't have the North American full EV mode. Their EV mode will turn on the engine on full throttle.

 

I can confirm that mine turns on the ICE if I push it into into the red PWR zone. I don’t find it difficult to keep it in ECO. The EU model also has EV City mode, where the same rule applies.

 

My 2020 Prius Prime will turn the engine on at full throttle in EV mode also. Not sure if its different than any others but if you stomp on the peddle it turns the engine on. I am in New England.

 

The American reporters and market got fixated on the 'EV experience'. It started with hybrids without a plug when people were asking what was the max speed the car could do in on just electric. It's a car fueled only with gasoline, with a battery too small to take it from zero to whatever that high speed is on electricity alone. As long as the car is returning great fuel economy, it is a number that doesn't really matter to the masses. EV speed became power to the hybrid crowd.

PHEV's came out, it meant blended ones were seen as inferior, when they were actually making better use a resources.

Does it turn as soon as the peddle reaches the floor, or later, as you approach higher speeds?
Could the car have actually been in EV Auto?

I see that @Dave7 also has a 2020 Prime. Perhaps Toyota switched American cars to the European EV mode recently.

 

I don't think so. I have not yet had any opportunity to press the pedal full-throttle, but the excerpt from the 2020 PP manual specifically says only EV-Auto mode would trigger the engine in this situation.

 

Are you in EV Auto mode at the time?

Our 2017 ‘Prime most definitely does not do that in EV Mode. I don’t know about EV Auto though, since I never use it. There are at least some reports that it does.

100% for certain, I have “floored it” in EV Mode many times on our 2017, and it has definitely never fired up the engine.

 

Especially in colder temperatures when you can make good use of the extra heat. In summer an unexpected warmup cycle would be less appreciated.

 

I almost always just drive the car. It starts in EV mode automatically, if I step on it the ICE starts. I'll try to replicate it to be sure but I hardly ever touch the mode buttons.

 

I've had my Prime for over 1-1/2 years and put over 20k miles on it. I've probably floored it hundreds of times in EV. The ICE has never started that way.

The only thing that I can think of (assuming no touching of defrost button, EV, or EVAuto buttons) is that the battery might be too cold or too hot to supply the necessary current for maximum acceleration and the ICE comes on to make up for the inadequate battery power. As you might guess, mine has been kind of warm but never very cold.

 

I hope not. That would be a giant leap backwards, This is one of the things that such and upgrade over the PiP.

 

OK based on everyone's input I tried to duplicate it and I can't so I must be wrong. Sorry I guess it must of been on EV Auto as was said. Strange as I start in EV mode but perhaps it was EV Auto and I missed it. Or the battery drained down and it went into hybrid. I was busy city driving and I tend to be preocupied with not getting hit and navigating thru.

 

Good sanity check; thanks.

Sometime I ought to try EV Auto to get a feel for how it works; never used it in the 3.5 years we’ve had ours.

Ironically, during these COVID19 days, were actually burning more gas, not less! Normally, I’d commute to work, charge there and commute back, all on electric. Nowadays, working from hike, locked up in the house all the time, we hop into the car and joyride, a bit beyond EV range.