Gas mileage

I've actually had the same question with my 2006. The changes versus this time last year are new tires and a much shorter commute. My last tank didn't break 30mpg and I'm quite a bit concerned. I did add air to the tires and it helped, but I still didn't break 30mpg. It has been cold here in Wisconsin, but we had a cold snap like this last year and I was still getting 40mpg. I get upper 40s in the summer.

I just filled up last night and made a 75 mile round trip, which included quite a bit of time on the interstate and the mpg average is in the upper 30s. Last year I had a 32 mile round trip commute and a good portion was state highway driving (45mph and I set cruise control for 54). Now I drive 9 miles round trip on city streets (30-40mph and I set cruise control for 9 over). What I've read in here is maybe since Little Red doesn't warm up to optimal temperature, she's not getting good gas mileage. I don't let her warm up (mostly because I'm perpetually late) on the really cold days and I opt for using the seat warmers instead of turning up the heat, considering it takes less than 15 minutes to get to work.

Any other suggestions? It makes me sad to see that average mpg screen with such a low number.


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You do not mention the brand, size, and model of new tires? If the new ones are not Low Rolling Resistance, they will not be as economical. You HAVE adjusted the air pressure, which is good.

Check your 12 volt battery voltage, a low voltage can lower MPG. Checking is free.
Weird stuff happening? MPGs dropping? Test The Battery | PriusChat

Consider grill blocking in cold weather. A cold engine is an engine that does not shut down at lights.

Consider and engine block heater in cold weather.
Engine Block Heater for 2004-2009 Toyota Prius - PriusChat Shop

I am sure others will suggest other ways to make you happier.

 

If you can, please post the brand, series, and tire size along with the pressure you are running.

A example of the data I am asking for would be like the following.

Bridgestone Ecopia 422 185/65R15 40lbs Front 38lbs Rear

Based on the info you provided I suspect the tires but cannot confirm this until more info is given along with the shorter commute. The Prius will suffer from cold weather and short trips, plus if you are not using LRR (Low Rolling Resistance) tires, the MPG will fall into the areas you are experiencing.

One other factor that comes into play is how you are using the climate control. If you have the heat set on HI the engine will run all of the time (not shut off at lights). If you can please post the temp you have the climate control set on and also are you using the AUTO setting with the A/C compressor running.

I do agree it has been exceptionally cold this year. I am beginning to question "global warming" now.

Best of luck to you.

 

Had to call my dad to find out what he picked out. It's been snowing nearly nonstop for the past 24+ hours so I'm not about to go outside to get the paperwork out of my glove box.

Primewell PS830/850
Car & Minivan All-Season
Size: 185/65 R15

Pressure is in the 40s, but I'm not sure the exact number. Definitely enough to make the warning light turn off (the next time I drove after I got the tires it turned on and the mpg went up after I added air).

I leave the temperature at but the fan speed low with just the lower and defroster setting (I had issues with foggy windows and read that was better than the defrost button). I remember still getting the gas engine to stop at lights when it's above freezing. Like I said, I rely on my seat warmers for warmth more than the actual car heater. I rarely increase the fan speed unless I'm driving with my friend's toddler or like last night when I forgot mittens. I turn it off completely if it's in the 40s or warmer. I never use A/C or auto because I know they're horrible for gas mileage.

My dad called me back to say he came across an article saying brand new tires tend to decrease mpg initially because they're more grippy (paraphrasing). I'll be honest, I'm completely clueless when it comes to cars and my dad is clueless about newer cars. I drove beaters up until I bought Little Red and decided to get the car I really wanted (ok, I really wanted a Ford Fusion hybrid but that was out of my price range). But I was super happy with the low 40s I got last year and want that back, especially since money is tighter last year.

And I believe the current term/theory is "climate change."


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PS830 & PS850 Passenger Tire — Primewell Tires

Under technology, it says None, so I suspect these are not LRR tires, so the mileage may be as much as 5MPG lower for the life of these tires.

 

Based on the above information and what is found online, I suspect the tires are not LRR type tires. So you can expect a loss in MPG due to that.

PS830 & PS850 Passenger Tire — Primewell Tires

I did not post additional links, however I did try to study as much as I could find online. I don't sell tires for a living...

EDIT: Jimbo posted same info as above while I was composing this. Sorry for the double post of info.

I would suggest you lower the temp to what is comfortable to you rather than HI. The ICE will run less often than if you have it on HI. Fogging up windows is usually caused by not using the A/C compressor while running the climate control on the "recirc" mode. Try using the "AUTO" mode, but turn off the A/C compressor (use the MFD) and set the temperature to what is comfortable to you. By doing that the cabin will be comfortable, the fan will operate normally and distribute heat as needed. Since you are using seat warmers you may find that 68 or 70 will be comfortable to you and you should get slightly better MPG rather than having the temp set on HI.

IIRC, the A/C compressor turns on automatically whenever you run the defrost on the windshield. The A/C compressor will cause the MPG to drop slightly even though it is electric.

That is correct. All new tires go through what is known as a break in period. It would not surprise me one bit if once you get about 5000 to 8000 miles on the new tires, that most of the MPG you lost will return. I can't say if all of it will return as I don't know what tires you had before. But once the tires are broken in, the MPG should get better.

Stay on top of the air pressure. Especially when it is cold outside. That one thing will help more than any. Remember to run two pounds MORE of air in the front tires than in the rear. Whatever pressure you choose, don't exceed the maximum pressure that is marked on the tire sidewalls. FWIW, the settings on the tire placard on the Prius are considered "minimum" and are designed to give you the best ride, but not necessarily the best MPG. Try running 42 Front and 40 Rear. If that is too rough of a ride, then drop the pressure a couple of pounds and try again. It is recommended to set the pressures when the tires are COLD. By COLD, that implies that the tires have set at least overnight.

Best of luck to you and I hope this helps you.

 

I'll try lowering the temp along with the other things you suggested with climate control. I s'pose if my commute is shorter and I'm not running the car enough to get it to really heat up, dropping the temp can't hurt.

Tell me more about this grill blocking thing. I think that might be my best bet outside of the temperature settings.


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First Grill Block/Interesting Results | PriusChat

 

Grill blocking will also help you. It is a good idea to monitor your ICE operating temp with a device similar to the ScanGage II

Prius radiator is actually two units in one. Top is for the gas engine (ICE), bottom is for the inverter and transaxle. Depending on your operating temps, you may only want to partially block the top. I may be mistaken, but I believe the normal operating temp to be around 180 Fahrenheit.

If you fully block your grill, it is strongly suggested that you monitor the temps and adjust the blocking as needed whereas you don't overheat the engine.

You can buy the ScanGage here on Prius Chat. They are also available at most auto parts stores.

ScanGaugeII : Linear Logic - Home of the ScanGauge

 

Bingo. That's the two most common reasons for loss of mpg.

The grill blocking might help a bit on the shorter commute (by allowing the engine to warm faster), but be real careful if you try this as you're effectively nobbling the engine's cooling. As Ron said above, you need to be able to carefully monitor the engine temperature, but the Prius doesn't have a temperature gauge!

Your new tires aren't low rolling resistance, and that can cost you up to 5 MPG on a Prius. It's true that the mileage hit can ease as the tires break in (you didn't say how many miles you've done on them), but you could still end up with a significant hit. We know the tires aren't LRR, but other than that we just don't know how good or bad they are. Different tires DO make a big difference though.

If you work out how much a 4 to 5 MPG hit will cost you (in gas) over the life of the tires you'll find it's about the same as a set of good LRR tires. So getting cheap tires on a Prius generally costs you money. It really needs a good LRR type like Michelin Energy, Bridgestone Ecopia or Goodyear fuel max (and others like these with a proven track record for fuel economy).

 

RaspberryConverse –Based on the data you have shared, my take is that there is nothing wrong with your iconic 2006 fuel-sipper that some warm Wisconsin weather, and Up-Pressured LRR tires would not fix. Because of the cold, your 12-Volt Accessory battery is probably under a bit of stress and seeing increased internal resistance, and your Traction Battery also does not “Like” the extreme cold. All these “Cold Ops” are causing your gasoline engine to run nearly full-time consuming precious fuel, and it follows that More Fuel Burned Equals Lower MPG.

What this humble Guru thinks he knows about you is that your preference for using the term “Climate Change” tells me you vote Democrat, your Prius is strictly a “Transportation Appliance” that you use to get you from Point “A”-To-Point “B” and back again, you are not a Do It Yourselfer, and you look to your Dad assist you in keeping “Little Red” percolating along.

The Primewell PS830/850 Car & Minivan All-Season 185/65 R15 tires should give you good winter driving service, but they ARE NOT LRR tires. Therefore, they alone, even if Up-Pressured, are likely impacting your MPG Fuel Economy by -3 to -5 MPG. They are new tires…you are going to drive on them for a few years…so you will have to live with this -3 to -5 MPG “Hit” come the summer of New Year 2014, and a few winters and summers after that until you replace them with LRR tires.

Since you are not a DIY’er and car tinkerer, and use your Prius as a transportation appliance, I would forget about considering using “Grille Blocking” to help you boost your running MPG. However, as a FWIW FYI for your edification, I have extracted some words about Grille Blocking from my "Ten Tips..." website:

"As an additional aid to accelerating engine compartment warm-up and keeping and running the ICE in the "Sweet Spot" temperature range that delivers Max-MPG-FE, some drivers operating in frigid Northern Temperate Zone environments (≤ 41°F/5°C Ambient Outside Air Temperatures [OAT]) partially block some of the space in part of the Prius front grille air intake louvers with cylindrical foam insulation like that used to insulate hot water pipes in your home.

NOTE OF CAUTION: Operating the ICE with the front air intake grille louvers partially or completely blocked off with foam insulation when Ambient Outside Air Temperatures (O.A.T.) exceed 41°F/5°C may result in harmful and damaging overheating of the ICE and propulsion components. Grille Louver Blocking should only be done when outside ambient temperatures will remain at or below 41°F/5°C throughout the day. Leaving engine compartment ventilation louver blocking material in the grille when O.A.T. temperatures rise above 41°F/5°C may result in damage to the engine, inverter and transmission.

People who venture to use grille louver blocking above 41°F/5°C usually have after-market ScanGauge II or similar add-on instrumentation installed so they can monitor the temperatures of the ICE and key propulsion components to keep them from overheating and being damaged."

I would invite you to click on the e-link in my signature, and give the “10 ‘Best Practices’ For Achieving ‘$tellar’ Fuel Economy In An OEM Instrumented Prius” material in my Ten Tips Guide a studied read. The effort will serve to make you a bit “Hybrid $marter,” and, if the tips and “Best Practices” therein are applied and practiced by you, they likely will raise your current wintertime MPGs, which are now running in the 20s, up into the 30s.

Have A High MPG New Year!!!

 

What do my my political leanings have to do with operating my car? And what is wrong with looking at a car as a "transportation appliance?" I'd say most people purchase cars with transportation in mind, though their choice of specific car may be for different reasons, and I chose the Prius to save money on gas, not as a status symbol or a hobby. Yes, I am pretty clueless when it comes to cars. Yes, I rely on my father for help because he is more knowledgeable than I am. If I have a question about something and I think a certain person might know the answer, I ask them. I know my dad doesn't know anything about hybrids, so I turned to this forum for help beyond standard car basics. What's wrong with that?

And apparently the tires I got for Christmas were a bad choice when it comes fuel efficiency. Oh well. Not much I can do about that now. I left the decision up to my dad because I really didn't know what tires to get and he was paying for them. Next time I'll look for reasonably priced LRR tires. Lesson learned. I thought learning more about the Prius was what this forum was for, but apparently it's also to criticize less knowledgeable Prius owners and their assumed political leanings. I'll keep that in mind next time I respond to a joke.


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Some tire places with let you trade them up for a better tire. There's been several guys here who have bought tires and been really unimpressed with the MPG hit and traded them in. I know you're likely to lose some money on the deal, it might still be worth it in the long run though.

Here's a UK site that sells those Primewell tires. In the UK they now have to give tires a "fuel economy" rating, and these ones only rate an "E". In comparison most decent LRR tires rate arbout a "B".
New Primewell Car Tyres | Primewell PS830 X/LOAD - 195/65/15 95T - 1956515

 

We've had a couple cool days here in Fl. , and both my Priuses 05/13 have lost about 5mpg right of the top.