Possible undiscovered performance and MPG issues with Prius v (lowercase v)

Hello,

I bought a 2015 Prius v back in October with now currently 2100 miles, and it still easily gets 43-45 mpg average per trip, while still driving at a natural and enjoyable pace. However before buying I rented a 2012 Prius v over the weekend and did notice that the mpg was less than the stated 40/44. And the 2012 model seemed to only get 37-39mpg, but still the Prius v with more cargo drives more natural and smoother than the regular Prius hatchback.

I'll list some possible causes and hints, since we both drive in Los Angeles County with similar roads and environments, these tips can be applied and hopefully help with your Prius v getting better mileage.

1. Accelerating: my previous car was a 2000 Honda Civic coupe, being smaller i was very use to a quicker spontaneous pace, so transitioning to a larger Prius takes a while to get use too. With the Prius v, you have to get use to accelerating slower with a lighter touch to the pedal, once you get into the 45mph zone you can step harder and then once you reach 60-70 mph you can lighten up and hold your foot mid way cruising at a steady pace however the freeway allows. Everyone assumes a Prius is slow, which is true in less than 45mph settings but at 60-70mph it cruises at a nice smooth pace shooting as straight as an arrow.

2. Switching Driving modes: I found switching and driving in these modes at various settings is best:
EV: in residential areas, drive thru restaurants, parking lots and when freeway traffic grinds to less than 10mph of stop/go.
ECO: Same situations as EV mode or when EV shuts off. Also when traffic slows to less than 30 mph. Can be applied on the freeway too when the road isn't too crowded by drivers who might be irritated with its slower acceleration and also on long roadtrips on empty high ways.
Normal: (all button modes off) Is good in regular city stoplight roads between 40-50 mph and is good on freeway over 55mph.
PWR: should be used the least since it uses the most gasoline, but it is helpful when merging onto a freeway onramp when the cars are all travelling fast, when passing up a slower vehicle like large semi trucks. And lastly is helpful when going up sudden hills. After a while Normal mode feels very similar to PWR mode during extended drive times.

3. Breaking: Get use to breaking at a further distance and try to observe a red light from far away. By letting the car just lose momentum before a red light and breaking at a further distance while applying a gradual pressure to the breaks, you give the regenerative breaks a better thorough charge, which will help with acceleration more effectively without using too much gas. Many people are unaware of the regenerative breaks, breaking correctly is what recharges the battery. This can also be applied when your going down hill, i've noticed the Prius almost engages into a very neutral feeling going down hill, just let it slide down hill as safely as you can, doing so conserves gas. Try to avoid sudden stops or stopping on a dime, doing this is a waste off gas and gives the breaks less of a charge, a sudden break should only be needed if your trying to avoid an accident.

4. Gasoline Brand: I know most people just gas up where ever they can find gas, but me personally I only fill up with Chevron gasoline. I've been doing this for over 10 years with my old Civic and now also with my Prius, and have noticed that Chevron gas always gets better mpg mileage. Filling up with 87 regular octane is fine, i believe the Techron chemical in Chevron gas really keeps your engine clean and running smoother which keeps mpg high. Before constantly using only Chevron, my Civic engine started to rattle and sound louder about 5 years in, when i switched to only Chevron gas, the rattling stopped and i got better mileage. My Sister's friend who is a mechanic for Honda can also attest to this, he only fills up with Chevron. In Los Angeles and California in general finding a Chevron gas station is fairly easy.

5. Temperature weather and Drive Time: Tempreature does affect your mpg, i wont go into the science of it, but they do affect the battery effectiveness in colder weather, and in warmer weather you actually do get better mpg, when it was 80 degrees average 44-46 mpg is commonly achieved. Then when El Nino rolled in end of December with the 50 degree average and 38 degree nights my mpg dropped to 40mpg, then rebounded back in warmer weather. Also drive time affects your mpg, i've noticed short city trips of less than 5-7 miles usually gets only 38-40mpg. It could be because of fewer use of the breaks and regenerating the battery, you use mostly gas. The Prius system appears to need a warm up time and when ever i drive for more than 7 miles or whatever 20 or 50 mile trips, my mpg really shines and gets 44-46 mpg. If you commonly use your Prius for short city trips less than 7 miles this can cause the mediocre mpg since your battery is being less frequently charged.

I hope this helps, what ever statements and observations clicked with you, i'd like to hear back.

 

Thanks for the thorough posting, lot of good thoughts. There was a member, MSantos, who used the expression "low hanging fruit". Meaning: things/strategies that are within easy reach, or easy to apply.

For your point #5, regarding warmup time and short trips, the block heater would help. I'm sure you'd get amused looks requesting this in California, but really: it's effective at speeding warmup anywhere.

With our low rates the electrical cost is trivial; I'd suspect even with higher rates you'd at least break even.

Also, real low hanging fruit: just avoid really short trips, walk it, or at least consolidate trips: as much as practical do them on the same day.

 

The thing that kills my v mileage this time of year is Wind more than cold. The cold does render it useless until warmed up, but the wind can be a constant. Despite its shape, the v in the wind feels like a box truck. My most recent tank of 33.8 is the lowest yet. Mostly highway, and headwinds were constant. I can tell as I drive the same commute how it lugs. Where the computer would normally show 35-40, it displays 25-30. Slight uphill, even at 65 mph the wind is pushing me backwards This is with warmer than normal temps this time of year.

With no wind and cold, it does far better.

 

Generally correct in your observations. Switching driving modes is probably not necessary, just leave it in ECO and you will automatically get the benefits of EV when possible and POWER when needed (with a hard press of the gas). I try not to Break my car ever, I always want to use the regenerative Braking to the largest extent possible. Gasoline Brand is important but not for the additive; instead it's the improved Octane you get with some brand names. Around here Exxon is better than most but Chevron is a good brand also. Just because it says 87 does not mean you actually get that, many brands cheat a little. Increased octane translates to more power or better mileage, however it's not worth the increased cost for Premium. Quite often you are buying the same refinery's gas at many different brands because they sell to each other at their product terminals. Temperature is also important.

 

I agree with the idea that shifting modes isn't generally desirable, and mostly drive in eco.

That said, there are a few exceptions in my opinion:

1) Since ECO mode will compromise cabin heating/cooling somewhat in order to shut the gas engine down more, I sometimes use normal mode to encourage it to control the cabin temperature better if I'm really uncomfortably cold/hot. That said, this comes at a cost of lower MPG.. but sometimes I'd rather burn a tad more gas to regain feeling in my fingers a bit quicker

2) I use EV mode when I'm only going to move the car a short distance. If I'm just backing my car down the driveway and parking it along the street, warming up the gas engine is a waste, so may as well use EV mode to prevent the car from warming it up. Shifting into this mode once warmed up doesn't make much sense, unless you know you've got a big downhill coming up and want to empty the battery as much as possible before going down it (knowing the large amount braking will fully recharge the battery). You really need to question yourself if you honestly think you can manage battery levels better than the computer can on average terrain. Yes it can be done, but you really need to think about the upcoming terrain features in order to do it (ie: you need to be better informed than the computer). Running on EV to the point that the battery ends up flat and and the car is forced to recharge off the gas engine while stopped at a light is NOT more efficient.

3) I sometimes use power mode when waiting to pull out into traffic, but that really only matters because it keeps the gas engine running and thus both the gas engine and electric power are available as soon as I step on the pedal.

AFAIK, Power mode also makes the gas pedal more sensitive in the early portion of the swing, and ECO makes it less sensitive, but both have the same power output when you have the pedal all the way to the floor. Thus, I don't really see a lot of advantage to "mode hopping" for things like passing in traffic. It just changes how far you have to push the pedal to get the amount of power you want.

 

power mode keeps the engine running?if you're pulling a trailer, get an airstream.

 

Ok, it isn't forced on all the time, but it is "less likely" to turn off, and more likely to be running and ready... I'll admit I don't really use power mode much, and have only had a Prius with this option for a short time (my old gen 2 Prius non-v did not have such an option).

EV, ECO and PWR modes | PriusChat

Purpose of Buttons (EV/ECO/PWR)? | PriusChat

 

gotcha, thanks!

 

The real question is WHAT did you NOT replace so far?

 

So

So Eco mode in a way is "Adaptive Mode" ? This is my first hybrid car, i always assumed Eco was the car's most conservative use of energy to optimize mpg. Or would Normal mode be adaptive mode ? Ideally I would opt for the Prius to drive in a manner that can detect what my present terrain or speed is and optimize mpg to that.

I manually change each button, particularly when entering the freeway when everyone is going 80mph, the slow drone of Eco just isn't safe. From what i observe in EV if traffic is slow enough really optimizes when traffic on the freeway is stop and go from 0-15 mph, I then switch to Eco when freeway traffic is stop and go 15-30mph, the mpg gauge would bounce in the 47-54mpg range.

Can the car really sense and engage the car to drive quicker when needed, even if driving in Eco all the time? I was unaware the Prius is capable of that.

As for "breaking" hehe typo, i hope my Prius never does that. And for gasoline brands its just a very long observation of 10 years that I've noticed and always stuck to.
Arco and generic stations = always get the worst mpg for a fill-up sometimes 10-15 miles less than i'm use to.
76 Stations = get a little less, but seem more punchy and robust when I press the gas.
Chevron = Always gives me better mileage sometimes 15-20 more miles on average. I don't know how but that's all i've used past 10 years.

I understand most stations come from similar refineries but every company does add different additives. And from what i observed when i first bought my Prius, the first tank from the dealer I only got 412 miles and on my second fill-up at Chevron I got 458 miles. Possibly the dealer did not give me a full tank, or just enough for the bar gauge to read full 10 bars.

 

i have never heard of this 'adaptive' mode. is it in your manual?

 

Oh no i'm speaking about Rjparker's quote to leave Eco on all the time that the cars' mpg will benefit and use PWR when needed. I was unaware of this and stated its like an "adaptive mode"

 

eco mode helps you not press the pedal too hard, but also reduces heat and a/c output. if you need quick acceleration, just punch it, no need to switch modes, it's exactly the same.

 

Okay yeah that's what i noticed it strains the pedal in Eco and lowers the A/C. In PWR mode it also doesnt do the engine stop/start at a red light. So if i just press the pedal harder in Eco it will give an extra kick ?

I've also tried to alternate driving in all one mode per fill up, all Eco during one fill up then normal at the 2nd and PWR for the 3rd fill up to see differences. I also get paranoid about driving in Eco all the time because won't that mean the battery is being used more frequently? than if I were in PWR mode?

I would like to avoid replacing the battery, i've heard of prius stories of driving 200k miles before any battery issues popped up. Could it be that they used the ICE more frequently and less battery via Eco mode?

 

yes.

no, you use less battery in summer with a/c on, and same the rest of the year. again, it's just holding the pedal back, not using engine less or battery more. you just accelerate slower unless you press harder. it's good for people with a 'heavy' foot, though they may get frustrated.

battery replacement is a lottery, but it seems more likely in warmer climes, and less driving. taxi's seem to do well in vancouver.

 

I'm going to offer my 2-cents worth here. I didn't completely read ALL your threads because they were lengthly but what I did get out of this is that I'm not sure if you considered the following: While it is true the software does a very careful dance to balance ICE power and EV power with user demand for power, it ALSO does this dance best over a certain temperature range. It is my experience with my 2nd Gen Prius and my Prius v, that the optimum temperature range (where it seems the Prius 'dance' offers best mpg) is 70-95 farenheit. Below this range the ICE tends to dominate and above this range I'm using the A/C and EV suffers. I understand this is absolutely normal and totally accept this performance. My highest mileage in the Prius v was 59mpg city and the outdoor temps were in the 80s.

A few notes to this end: First, When running the heater the ICE will run more often to maintain hot water supply for the heater (yes, the climate control is smart enough to demand ICE when is senses there is insufficient hot water). Second, the colder temps causes the ICE to run a bit more to maintain transaxle temps in good operating range. And, when running A/C, traction batter demand is greater to run compressor and hence, ICE runs more to recharge it. And Third, if you want optimum mpg performance in any driving environment, you've got to learn to modulate the gas pedal better. That is, be a somewhat lightfoot driver and remain concious of energy demand, and, learn to operate the ICE "on the step." That is, once it is sufficiently warmed up, get your cruising speed above 46-47mph and back off slightly on the pedal. You'll see your instantaneous mpg spike. Then strive to keep it there and you'll be amazed of your incdreased overall mpg.

My 2nd gen works the same way. Hope this helps you.

 

Yeah, I've found I can turn the engine on/off, when sitting with engine off, say at a red light, by raising or lowering the cabin set temperature. Tick it up one degree, engine comes on; tick it back down, engine goes off.

 

all good points, i don't understand why krill is being so obstinate and refusing good advice for his low mpg's.

 

reread the post. Krill has driven many prius’
"I had to purchase them one after another and ship in sequence. I purchased two Prius v 5 2012 20K and 27K with manufacturing date 02-2012. Cars were just one year old. Both cars had weak EV output and poor 35mpg. Before I shipped them out of country, i drove about 4k miles on one car and on the second one about 1k. I figured that there is just possible design features from the plant of Prius v but I should say that I really like the car.
Soon after, a couple more cars were purchased with manufacturing date 9-2011 64K and 01-2012 18K. Both cars drove excellent! MPG was about 45-50 and good EV acceleration. Seeing it really changed my opinion about Prius wagon. I decided to buy v for my personal use, but unfortunately i purchased car with manufacturing date 02-12 :-( The one that drive feels like I’m towing a trailer and gives only about 35-36 mpg."

 

someone needs to swap trannies.