2023 LE fwd mpg, what are you getting?

For real. Back on track! For those complaining about poor MPG I finally got a glimpse as to what you cold climate folks go through. Got kicked out of the garage last week and we had sub freezing mornings. Idled the car 10 min to defrost windshield and ran heat on high all the way to to work on a particularly cold morning and instead of my normal 50-55 mpg morning commute I got by far the worst fuel economy number for a trip that I have ever seen at 35.7 mpg. Normally for me anything in the 40's is really bad and I have had most tanks average high 50's to low 60's for mpg. Also notable to get 26% EV driving ratio vs the normal 50%.

Still averaging 52 mpg on this tank after 150 miles but cold mornings like this sure kill the economy.

My RAV4 Prime would kick on the ICE in EV mode if I ran full front defrost. Seems the Prius is similar in programming as I can't even backup into my garage on cold mornings without the ICE coming on and running almost non stop.

 

The cold will absolutely ding you! Idling in the cold is a double ding. Sorry you got kicked out of the garage. Try and use the regular floor/defrost function set at 60f instead of the dedicated defrost button, when you can. I think the fuel penalty is lower, particularly if the AC stays off.

I wish I would have tracked my fuel economy in the G4 during winter closer. I seem to remember it was in the 50's though.

 

And they said you couldn't drift in a Prius...

A few Priuschatters are skilled enough to do the Scandinavian Flick by keyboard. Respect!

 

I think Toyota programming for the whole HVAC system is really lacking. For example, in my prime if I put on the front defrost the engine turns on in EV mode. Probably it's trying to add heat and AC but that's not what I want. What I want is all the air going to the windshield but of course there is no option for this setting. If I turn on the HVAC before going out in the morning to precondition the car it ONLY uses recirculated air so the windows all fog up completely negating the benefit of preconditioning the car. If I go down a hill and have the heat on and the fan on high the engine turns on for reasons I cannot even fathom. If I immediately pull over, turn off the car, turn it back on, I'm back to EV mode. Toyota builds a pretty good hybrid but they SUCK at EVs.

 

dude just said he tried to idle and use defroster in a hybrid lol

 

Just hit 1,000 miles and one month of ownership. Averaged 47mpg with a lead foot in all driving conditions. doing between 65-80 on the freeway

 

You can direct air to the windshield (and feet at the same time). The airflow mode setting knob is just to the right of the fan speed setting knob. It's in Section 6.1 of the manual. I never use AUTO mode myself.

 

I know....crazy right? Don't tell anyone but I also don't hold up traffic, drive 10 mph over the limit and sometimes go full throttle from a light to leave the walking dead behind.

Seriously though I did it just out of curiosity and partially to just understand what is the worst gas mileage I can get out of the car. Trying to see if there is even any overlap of best MPG out of my last few cars (FK8 Civic Type R, GR Corolla, GR86, C8 Vette, A90 Supra, ZL1) and the worst I can get out of the Prius. So far under normal use the Prius stays over double the MPG of even the best efforts of previous cars under similar conditions.

All in the name of science (and keeping this tread about MPG baby). Unfortunately I am missing out on a golden opportunity for worst gas mileage ever as my friends are all at the track today....they rented out the local road course for a private test day (open track all day with 20 people and open passing) and I really thought about putting some summer tires on and seeing what she could do and still kinda wish I had gone and just played around. Had a deal on a FL5 Type R fall though (dealer greed isn't decreasing as fast as the economy) is so kinda had my eggs in that basket so lost focus on getting tires for the Prius.

I gave up "semi hypermiling" for the winter and just driving this thing like a normal car which is surprisingly fun and still amazingly efficient.

 

Wasn’t talking about gas mileage. I was talking about how idling never produces heat in a hybrid unless you have the prime. That’s why I never dealt with remote starts for hybrids or after market one. Summer AC would be great, but hot air while idling? Not possible. Gotta drive to actually heat the engine up.

 

That's absolute rubbish for a gen5. After reading your post, I just had to get empirical data. It's currently 13F in my location and my car was outside and unmoving for about 24hrs. I ran a single autostart cycle(10min) and then went to the car with one of my accurate(and calibrated) thermometers. I went a little over 10min, so the car had shut off for a couple minutes before I got in. I started the car, switched the HVAC to dash, and stuck my thermometer probe in one of the dash vents.

Within 10sec, it was blowing 80F air. That quickly rose to 105F within a minute.

On the way home after trivia night, I ran two autostart cycles before heading to the parking lot. The car was blowing 105F air immediately upon getting into the car.

Idling absolutely, without a doubt, is enough to generate hot air in a 2023 HEV Prius. (Also many other hybrids, but I don't have empirical data for those.)

 

if you or anyone else uses car scanner app and an obd11 bluetooth adapter, it's easy to see pretty closely what the cars coolant temps are and how long it takes for the coolant to warm to a temp that provides cabin heat. That time will surely change with ambient temps, drivng style and speed(s) (when not at idle) and wind speed and direction relative to direction being driven ( is applicable ).

A prius behavior can be way different from one owner to another.

Than again it seems hard to imagine a prius idle warmup cycle taking too long for some owners or worse being describes as non-existent or infinitely long.
But I must admit for anyone that watches prius mpg, that time and mpg drop can seem infinite or almost infinite at times, due to how fast mpg can drop from normal prius mpgs, under several conditions

 

In this particular case, I care more about the air temp coming out of the vents as opposed to the coolant temp. The reason is because he specifically said you couldn't get hot air while only idling. I'm trying to eliminate all variables except air temp, outside temp, and time. I don't care if the coolant temp is low if the reason it's low is because the car is sucking the missing heat into the cabin.

The forecast for me this weekend is for a daily high(Sat -4F, Sun -5F) that is just below Portland's(the poster's location) record low(-3F). Winds are predicted to be 15-25mph. I plan to run the autostart and take temp readings at 5min, 10min, 15 min, and 20min(if needed). Sunday's low temp should be around -15F w/15mph winds, so I might try to test then too. It seems like 105F is the car's target air max temp, so I'm going to test if it can achieve that at idle, and how long it takes to get there at idle. (I'm also going to test if 105F is the real target max temp, or if it just appeared that way with my limited data points tonight.)


Look, maybe previous generations of Prius HEVs couldn't get their air temps up at idle. I owned a gen3(2010) for many years, but it never had an autostart installed. I know it took over 5min to start throwing warm air on a really cold day(gen3 HEV didn't have the grille shutters, for one thing). Often it started blowing warm air(not hot) just as I pulled into my destination(6-8min commute). But this is the gen5 forum, not the gen3 forum, and things change(different engine, grille shutters, etc.). My experience this winter is that my gen5 starts to blow warm air within 5 minutes at idle, and blows fully hot air within 10 minutes at idle. That's with ambient temps in the low teens.

Hey, if I'm wrong, I'm wrong and will admit it. But phase's statements feel like old wives tales at best.
"I was talking about how idling never produces heat in a hybrid unless you have the prime."
"Hot air while idling? Not possible."

 

Just an fyi - if you're open to others data points, the Gen 4 grille shutters, much like the Gen 4 heat pump, work at providing ( some ) benefits to the prius warmup cycle, but they both can be enhanced with a bit of experimentation and monitoring.
Kudos, for taking the time to document and know exactly how your prius behaves with the conditions you have in your area.

 

Ahhhh...gotcha. Does it not work in your 2023 Gen 5? It doesn't take long to defrost my windshield just idling in my driveway and I have warm air out of the vents in less than 10 min. I am not in super cold climate but it has been below freezing several mornings and mine defrosts just fine while idling.

Definitely doesn't heat up as quickly as my 23' Tundra "hybrid" or 4runner but it works pretty much just like a small engine car. ICE runs non stop while defrost is on which totally kills gas mileage but seems to heat up fine for me.

 

You'll get heat; it isn't a diesel. There just was a good chance you used more fuel to get that heat than starting the trip after engine start up. Just a question of what your priority is.

IIRC, the gen2 had a set of resistance heaters to help out while the engine was still cold. Maybe there still is.

 

Well that’s nice to know that heat happens much quicker in gen 5. I know it was bad on older Priuses and even my personal Hyundai Ioniq hybrid doesn’t provide any heat when idling. Heck if I’m doing stop and go traffic, the engine shuts off at every red light and doesn’t give me heat. It’ll have some warm air then start blowing cold air again once I’m at a stop light. The only hack I can do for warm air is to put it in sport mode and drive like a maniac in stop and go traffic or I have to go on the highway and get RPMS up. If I stay in a small ski town and it’s just city driving to get to the ski resort from the hotel, I’ll never get heat ever. I’ll have cold air when I arrive at the resort. It sucks

so thanks for letting me know Toyota has upped their game from previous Priuses and definitely from Hyundais hybrids.

 

That isn't just the front defrost vents so isn't the same amount of defrosting (or defogging). If you DO turn it to defrost it fires up the engine. It's a bad design. You should ALWAYS have the option to override the programming. A car has NO IDEA how warm or cold or anything you are.

 

What are you talking about? Of COURSE it produces heat by idling. Idle burns fuel that heats up the engine that circulates water to the heater core (and not the radiator unless the thermostat is open) which heats up the car. A hybrid may have OTHER heat sources as well but THAT system works off waste engine heat. Now it might not idle much, true, but in the Synergy drive the engine runs until it comes to temperature even in stop and go traffic. THEN it shuts off when not needed.

 

If your Ioniq isn't producing heat from the start stop cycle then I would check your thermostat. A properly working cooling system is shut off from the radiator until the temperature reaches the point where it exceeds the thermostat temp, then it opens. The HVAC system isn't in that shut off so gets water all the time when the setting is turned to heat (via a valve). If one of those isn't working properly you won't have heat. But in any hybrid the engine should run at full idle until the temperature is correct. This should be a sensor and if that isn't working correctly it would also cause this issue.

 

As soon as those temps come up, we're back in business.