Im only averaging 40 mpg. Is that normal this time of year?

http://priuschat.com/forums/gen-ii-...-answer-these-questions-esp-if-youre-new.html

Your cold temps and hills don't help. Your snow tires don't help either. The bolded part is not a good thing. It's best not to accelerate so gently so that you still in electric only. There's the so-called hybrid paradox of the fact that you have the battery but to get best mileage, you need to minimize its use.

http://priuschat.com/forums/gen-iii...mileage-gets-worse-in-winter.html#post1411488

 

...the survey will tell us if you are doing many short trips. Short trips you probably noticed the Prius does not get up to full MPG until after 10 minutes or so.

 

By all means, complete the questionnaire pointed out by cwerdna.
Complete answers will help us identify one or more of the many little things that could
be contributing to your low MPGs.

There are numerous "usual suspects" for lowered MPGs.
These would include:
* Tire/tyre type - LRR preferred, 5K mi break-in period
* Tire/tyre pressure - 40/38 psi front/rear, but not above max sidewall pressure
* driving at speeds in excess of 65 MPH
* 12V battery condition
* short trips - I consider less than 10 miles "short"
* traffic moving at less than 20 MPH; heavy HSD use of EV mode
* low air temps - below 40 degF, HSD will run ICE to keep the Catalytic Converter warm
* use of heater/defrost, HSD starts ICE at stops when coolant temps fall below 145 degF
* water on roadway - 1-5 MPG hit from just barely damp to standing water
* Junk in the trunk - extra weight in car
* "Winter gas" (where applicable)
* Dirty throttle body
* Dirty MAF sensor
* Clogged air filter
* Alignment - rear axle misalignment is rare and difficult to fix

There's one thing that you've said that could be a big contributor:

Yes,

See this post for the reasons why trying "keep it in electric," EV Mode, is the
wrong thing to be doing: :nono:

http://priuschat.com/forums/gen-ii-...uel-while-frequent-stop-go-s.html#post1487373

:doh:

 

how many miles is your commute each way? i have 7 each way half highway and half 30-40 mph. not too may hills and i'm getting 55-60 in similar weather. you need to learn pulse and glide instead of feathering. you can lose the snow tires, it's going to be warm until next winter.

 

I noticed a couple of big problems in your response.

Tires: Winter tires will really hurt mpg. This is especially true for non-LRR tires. Winter tires that don't seem to hurt mpg so much are Michelin X-Ice Xi2 and Nokian WRG2.

Commute: Your commute is pretty short and likely not long enough for the car to fully warm up. The first 5min of a drive is typically only worth 35mpg or so. You're already grille blocking so there is not much else you can do other than an engine block heater.

EV Mode: Don't try to use it. it is less efficient than burning gasoline to move the car.

Technique: you state you are "gliding" by letting off the gas pedal completely. Stop doing that unless you need to slow down faster. It is better to anticipate your next stop and start gliding well before the stop. A true glide is performed by lifting off the gas pedal then gently reapplying a little bit of pressure until all of the arrows on the MFD disappear. If you are traveling over 42mph you will instead go into warp stealth. The principle is the same but over 42mph the arrows will be shown moving from the HV battery to the wheels. This uses very little energy and is the ideal state to be in when above 42mph and anticipating a stop.

Additionally, you do not want to put the car in neutral for enhanced mpg. If you do so the injectors will continue to pump fuel into the engine and the best you can hope for is about 350mpg. If you instead entered a glide or warp stealth you will get infinite mpg or 9999mpg as shown on the Scangauge II. Neutral should really only be used for emergency purposes like unintended acceleration. But since that never really happens you should never need neutral.

 

In those temperatures, with that distance and length of commute, I don't think you'll see above 45 MPG until it gets warmer out. I live 10 miles from my work, and it's about a 15 minute commute, and it takes all the way until the last 1-2 miles before my mileage starts to climb above the mid-20s to mid-30s when it's that cold out. I'm lucky to reach 45 MPG by the time I get to work and if it's below 27F I may be lucky to reach 40 MPG by that time. However, once I'm at work and my car has had that time to warm up, then I can keep it in the mid-40s or even get into the low-50s as long as the temp stays above about 27F.

When it warms up, you'll probably get closer to the 46-52 MPG range with a commute like that based on my experiences. Your circumstances might be different than I imagine them to be, and you might drive differently so my estimates may be off a bit, but I think with warmer weather you'll get closer to the 48 you were hoping for. At that point, the commute length will be what kills it more than anything.

You can mitigate some of that by learning about the "stages of operation" and what the "rules" are that the Prius uses to decide which stage to use, and how to exploit their limitations with your commute to your advantage. For example, on a commute that short in cold weather, it's likely your car never gets warm enough for full hybrid operation (known as stage 4, which requires reaching full operating temperature-- engine coolant temp of 159F-- as well as a complete stop with the engine idling for at least 7 seconds and coolant temp remaining at least 159F until the 7 second idle check begins). So if you wanted to use pulse and glide to save gas when you can't reach stage 4 operation but you can still reach stage 3, then you'd have to make sure to speed up to at least 35 MPH before you try to glide or else you won't glide as well as you could, and you'll also still be burning gas in the process. But if you can burn a little more gas to get up to 35 MPH before gliding, then the engine will shut down and you'll glide further on less gas over all. Things like that are how you can squeeze out that extra inch, and many of the techniques become second nature once you learn them.

 

This hurts mileage. In colder temperatures the car may not even warm up properly.

This is a hindrance, but overall hills aren't as bad as you might think, especially if you can keep the power down up the hill.

This definitely hurts mileage. Try removing some of the oil.

Please check the voltage.

If the 12V is losing charge, the engine has to run more often to keep it charged. This has a negative effect on mileage. It's a very noticeable negative effect on mileage and with all the problems it causes many people wish the car would tell drivers when there's a problem with the 12V battery.

Winter tires hurt mileage. That's some of the hit.

That's helping your mileage.

Don't try to stay in electric. Yes, you can use some excess when you know a regeneration opportunity is coming but only then.

You really want to be gliding, rather than coasting. Glide requires you to have your foot very lightly on the gas pedal. In order to provide behavior that people consider typical of an AT, the Prius simulates engine drag when you take your foot off the gas.

Keep out of neutral (for now). Not only is it mostly inefficient (it can't charge the battery) but potentially it can damage the Prius' hybrid system.

Don't fight to stay in EV mode: you either want to be gliding (or barely on EV) or using the engine. But try to be easy on the engine when starting since it's so inefficient. It sound like your commute gives you the opportunity to be easy on the engine for the first few miles.

However, I actually suggest that initially you
- remove the excess oil
- check your 12V battery voltage and report back. The experts here can advise you whether you need to replace it.
- just drive the car rather than trying too hard. Driving normally (generally efficient techniques like timing lights are OK, but avoid things that need to be tailored to the vehicle like pulse and glide and using neutral). That'll give you more of a baseline from which you can vary your techniques to try and improve the mileage.

 

You're doing all you can, except: accelerate more briskly. Be happy knowing that MPGs will improve noticeably when outside temps increase and the snow tires come off. Please don't take a longer route to work just to increase MPGs :_>

 

It sounds like you are doing quite well. I think the colder weather combined with short trips is the main cause of your earlier disappointment.

You are clearly motivated. I highly recommend reading up on and practicing pulse and glide driving if you can often let your speed vary freely below 40mph. In warmer weather and longer trips, I think you may be motivated enough to maintain a 60mpg average and to best 80mpg when the conditions are right. I really like what Wayne Gerdes, Ken, and others at cleanmpg have written.