New owner? Want MPG help? Read this first.

I received my 2008 Touring a few days ago. Getting a somewhat disappointing 41mpg for the first 140 miles. I'm taking it easy and trying to maximize the mpg. 80% suburb driving. The air filter is a bit dirty so I cleaned it and intend to replace it shortly (cabin filter too). Oil is fresh and proper level. I just raised tire pressure from 32 up to 40 on all corners. Any other suggestions of items to check? I know 140 miles is too soon to get crazy, but heck, that's why we are here .... right?

Well, I finished my first tank (one bip left) with 44.82 calculated. Put in 9.55 gallons. A bit disappointing but it will take a while to get a real average mpg.

Miles driven per trip and road/environmental conditions vary for everyone so don't be disappointed if you never see stellar numbers that some PC members put down. Fuel formula also plays a big part as some areas of the country don't use E10. Keep practicing your glide and reduce the number of short trips you take and your numbers should come up.

I bought a salvage title 2009 Prius in August 2009. It had 4000 miles on it. Now it has 13,000. My mileage ran about 45 on ARCO regular gas until June, when I had the A/C fixed, and it immediately jumped to 47.

About 3 weeks ago, I bought a tank of Costco gas. I had a free 3-month membership, and I was at Costco when the tank was empty, so I filled up.

For the first time, my mpg topped 50, and even went up to 51.5 at one point. The driving conditions, temperature, tire inflation etc., had not changed. Average mpg for 452 miles was 50.5.

Then I bought a tank of ARCO and it immediately dropped back to 47.6.

Today I bought a tank of regular 76, just to see what happens. To get more Costco gas, I would have to join. The low price and better mileage would make it worthwhile, but I want to see if any of the nearby stations have gas that works as well. Costco is out of the way.

Re MPG
New owner of an '04. 80K.
The display has now failed to the 'check AC connection' etc. There are many posts on this and clearly I am in for a hit in the pocketbook if I ever want to see a functioning display.. but....
Does the display not functioning properly directly affect my engine vs battery operations?
Am I dreaming or has my MPG dropped considerably since this failure.

My last tank was 10.5 gallons. The display showed 49.5mpg (my best yet). When the pip started flashing, the mileage total was 461. I filled up the tank again at 10.5 gallons, so the ACTUAL mileage was ~44mpg. That's a 5.5mpg difference between computer reality and reality-reality. I have never under any circumstances managed to get the mileage some of the people on this board claim. I had the same issue with my Jetta TDI and the TDI forums. All of these guys were claiming in excess of 50mpg on their Jetta TDIs, yet I never got even close to that. I maintain my vehicles and am hardly a road racer. It is my belief that region has everything to do with mileage.

You CANNOT perform such calculations with a single tank of fuel on the 2004-2009 Prius due to the bladder-based fuel tank. You MUST perform the calculations using a large number of tanks if you wish to get an accurate estimate of your true mpg vs. the calculated mpg displayed by the car. This has been discussed ad nauseum in this forum. Other drivers, who have diligently tracked their mpg for years, have shown that the difference between hand calculated mpg and the displayed mpg is actually quite small.

I agree with the last part of our comment. Region does play a large part in observed MPG but commute and driving style plays an even larger role. I can change my MPG average by as much as 8+mpg just by changing my driving style or my commute pattern.

Dear All
As I read Posts ,I conclude that all new owner said the if they have a short trip ( milage) the fuel economy will be bad , is'nt it ? In my case my work is near my home approx. 5~8 kilometers and we have hills and mountains road , I think the prius will not warm enough to reach it maxiximum economy milage , all my travels inside my town, and my town is very small each trip only 5 to 10 minutes drive, maximum 10 kilo meters , how can i improve my fuel consumption which 8.1 L/100km ~ 28mpg ??

thanks for the info and the link
not looking anymore

Real quick guys, i got my mud guards in today and ill have to take the tires off the car to put them on. I read it somewhere but cant find it.....what should i torque the lugs back on at. I thought i read 78 lbs....is that correct? Thanks.

Hello all,

I was on here a few months ago wondering why my gas mileage had dropped in the winter. I learned that a cold battery has less power than a warm one. Plus I realize the ICE runs more often in cold temps to keep the heat flowing. Also I was playing with the accelerator pedal, trying to extend the EV mode as long as possible and a senior member of the forum told me that was not a good idea, because acceleration requires a lot of power and the Prius is not an EV. The computer detects power demand and enables the ICE appropriately.

Ok, so the winter is gone-70 degrees here the past few weeks (although the past few days the temperature has dropped back to 40 :-/) and I'm extremely frustrated because the car is getting 38 mpg. I do deliveries for a catering service, and wanted the Prius because it's roomy and is supposed to have "wonderful" city mileage. The city driving I do is over moderate hills and stops and starts occur (on average) every 5 minutes or so. I don't floor it, but because of that post about "prius not an EV" I also don't baby it. The driving mix is probably 70% city and 30% highway.

I've read through a couple of different threads and found that turning off the "A/C" button seems to help-which I have not tried yet. I performed the voltage check on the 12V battery and it was normal. I read all over this site about people getting 45 mpg (at the low end) and 55 (at the high end) in Gen II Priuses (mine is 2005 if it doesn't say in my info). This makes me want to scream. I love the way the Prius rides (except around corners) and plenty of room to load food in. I have JBL sound, which is awesome, but why is my mileage so far off?

My parents live in a suburb of Nashville about 40 minutes from downtown (where I work). Recently when I've been driving out to see them, the car gets 48 mpg highway. This is obviously a ridiculous improvement over the city mileage. What puzzles me is that when I bought the car (in June 2010 with 85k mi) I drove it from Venice, FL (where I found the one I wanted at an appropriate price) to my home in Nashville (14 hour drive) with an average of 43 mpg highway. In the city, I got the exact same mileage. After rummaging around the forums, I figured it was just lower than the low end average owner mileage and not a big deal. But since the weather has warmed up, the mileage has NOT improved.

When I posted in the other thread about poor mileage in the winter I had a fear of failing HV batteries. The warranty is about to expire (100k) and I am going to scream (again) if they go on the blink after I pass the mark. My grandmother has a 2005 Avalon that she drives much like I do (average-to-brisk acceleration, more in the city than on the highway) and she gets 30.5 mpg. What the hell? That car has a 280 hp 3.5L V6. And my prius with a 1.5L I4 plus battery assistance gets 7.5 mpg better?! I'm thinking I should have just kept my Impala with a 26 mpg average and 3.8L 200 hp engine, even though the thing was constantly in the shop. Help, please.

P.S. To answer your questions, the tire pressure is what is recommended on the driver side door label. The air filter is clean. I read the articles about how the EPA estimates are off and how you can change driving habits to make it better. When I used to play with the pedal as I mentioned above, the best I could manage was 46 mpg in 70 degree weather.

Correct, do not try to accelerate in EV only in the hopes of getting better mileage.

No, the mileage drop due to cold weather isn't only due to a cold battery or "heat flowing". Please see Why does mileage drop in winter? — Autoblog Green
Cold Weather Vehicle Fuel Mileage – Why Winter Fuel Economy Drops – Fuel Mileage Drop in Vehicles
Car Talk
Why does gas mileage drop in winter? | StarTribune.com.

Your mostly city driving and the starts and stops are what's hurting your mileage. The hills don't help either.

I don't know how long each of your trips is, but if each time you shut down the car for too long, the ICE is losing heat. If they are short drives, that's killing your mileage, esp. if the engine never even gets fully warmed up before the first power off.

How long are your trips in time and distance? (count the time between a power on and a power off) How long do you stop for between each power off and on?

I have an 06 and my lifetime average is ~45 mpg and falling. It used to not be falling when I had a long commute. I could get over 50 mpg on a "tank", if I kept my highway speeds below 70 mph for an entire tank. Now, I have very short city drives and am lucky to break 40s on a "tank". It's not surprising.

It sounds like you have some expectations based upon EPA estimates besides what people are reporting here. Please read http://priuschat.com/forums/other-c...uth-about-epa-city-highway-mpg-estimates.html and compare their cycle and test methodology to your drives.

Please read http://priuschat.com/forums/newbie-forum/91431-one-3.html#post1287385 about better managing heater use. If you are using "auto" mode on the HVAC, don't.

Don't know anything about the latter drive or conditions or esp. the speed of the drives.

Trade cars w/your grandmother. You will get a lot less than 30.5 mpg on your catering drives. I wouldn't be surprised if you can't even get 60% of the 38 mpg you're reporting on your Prius.

As for your Impala, I suspect it would've gotten worse than 26 mpg on your same trips.

Please see Most fuel-efficient cars where CR got 35 city/50 highway, 44 mpg overall and 48 mpg on a 150 mile trip. Notice there's not a single vehicle there that gets better mileage than a Prius, be it overall, city, highway or on their 150 mile trip?

On comparison, here's what they got on a:
05 Avalon XLS w/3.5L V6: 15 city/33 highway, 22 mpg overall, 26 mpg on 150 mile trip
06 Impala 3LT 3.9L V6: 13 city/29 highway, 20 mpg overall, 25 mpg on 150 mile trip
04 Impala LS 3.7L V6: 13 city/31 highway, 20 mpg overall, 24 mpg on 150 mile trip

More Prius data points fleet testing fuel economy at http://avt.inl.gov/hev.shtml and http://priuschat.com/forums/gen-ii-...edmunds-long-term-test-wrap-up-04-prius.htmll. Keep in mind Edmunds is in LA, their long term cars are swapped between many drivers, they don't seem to drive for fuel economy and LA traffic is terrible w/lots of stop and go + aggressive driving required on the highway.

The above pressures are too low. People who are getting on the higher end of mileage figures do NOT drive at door sticker pressures. BTW, what's the exact make, model and size of tire that's on your car now?

- Are you driving in B mode? If so, don't.
- Is your oil overfilled?

You should also consider grille blocking in cold weather. I do as do many of the higher mpg folks. If you have no means of monitoring ICE temperatures (like via a http://www.scangauge.com/), I'd remove all your blocking if the outside air temps hit say 60 F, unless your drives are REALLY short. I'd also leave an opening in the driver's side of the lower grille to allow for the inverter and transaxle to get incoming air.

I recently stumbled across http://www.cleanmpg.com/forums/showthread.php?t=17560 re: grille blocking. I can't vouch for the accuracy (or lack of) of the "How much blocking do we apply?" though.

That's probably got a lot do do with it. I find I get my worst fuel economy in hilly terrain, in particular where the hills are steep enough to cause the instantaneous MPG to fall down below about 20 to 25 MPG when climbing. Also it's especially bad when the terrain or traffic conditions are such that you need to climb slowly or where you can't maintain your momentum at that start of the climbs.

Interestingly however, I also get my very best fuel economy sometimes on hills, but hills that are more like gentle undulations rather than steep. These are hills were even though you're ascending you can still keep your instantaneous MPG mostly over about 35 MPG. Now if the speed limit is low like 35 to 40 MPH then even though these hills are gentle it's still enough to use zero fuel on the descent. So on average I'm getting like 70+ MPG sometimes on this sort of terrain. Niiiiice (as Borat would say).

Ok, feeling better after reading cwerdna's post. Basically what you're saying is math is a great way to oversell the mileage of a car and most people aren't getting what they think they are. I am aware that the EPA tests are atrocious for determining a car's mileage.

The tires on my car are Yokohama AS530 185/65R15. The driving conditions on the commute to my parents' house are 70% interstate at an average speed of 70 mph, and 30% city with 3-6 stops about 5-8 minutes apart. [There is one stretch that is completely flat for about a mile and if I go exactly 40 mph (the speed limit) the car stays in EV mode the whole way and I get excited :-P] The speed of the city portion in this commute is much more gentle (I loathe suburban drivers).

I will not trade cars with my grandmother. For all the die-hard Toyota fans out there, brace yourselves. The Avalon she has (base) is basically the same as the Park Avenue she had before that with better reliability and more power (I'm not even kidding-same exterior and interior colors-same beige wheels-bless her heart, she's so cheap she'll take whatever car on the lot).

The time between button power on and off is on average 10-20 minutes. If I don't follow the tire pressure on the doors, what should it be? Should I worry that I'll wear the tire treads only in the middle for over-inflated tires?

Lastly, my only other grievance with the Prius is the mattress-like handling around corners. Granted, I know it was not built to be a Ferrari. The car is approaching 100k mi, which I heard from someone is the time to change shocks or struts (or both-I'm not sure). Maybe the suspension is worn out? Or is that just the way it drives? Can I put stiffer equipment on and notice a difference?

Thank you to anyone who weighed in on this post, especially cwerdna. I wasn't planning on getting a new car even if I was experiencing mileage anomalies. What can I say, I love my car! Also appreciation for reading what I write; they are novels for a forum ;-)

hey, thanks for such an impressive and detailed reading you provided. It will help.
Thanks

Thanks for that article, it is a big help. But I'm still stuck. I bought a used 2007 Prius in April (and I love it!) and have been getting average of 40-42 MPG. I have been happy with that based on my driving habits. However, this last two weeks my MPG has suddenly dropped to an average of 32 MGP and I can't find out why. I may have had a few more short trips, not allowing my car to get to the full temperature but not too many more out of my normal routine. Any ideas what I should look for before I take it in?
Thank you!

Check your 12v battery. Ensure your tires are properly inflated too.

Problem: 12V auxiliary battery failure
Symptoms: Unusual MFD warning messages. Weak cabin lights and headlights.
Frequency: May be intermittent initially
Diagnostic: Measure battery open-circuit voltage. 12.6VDC or greater indicates the battery is fully charged. 12.2VDC indicates 50% charge. However, note that battery voltage is not a perfect indicator of battery health as excessive internal resistance will result in the battery not being able to deliver sufficient current under load.
Cure: Replace the battery. The correct Toyota battery can be purchased at your Toyota dealer's parts counter. Note that two sizes are available; the smaller size is for base models while the larger size is for models with the Smart Entry / Smart Start system.

Some posters have been very happy with the Optima battery, but this requires installation of a new positive battery terminal connector and replacement of the negative battery cable.
Other information/Alternate diagnosis possible: If you have weird electrical problems and the battery is more than 3 years old, I suggest replacing it as a preventive measure and to rule that out as a cause of the problems.

Even if your car currently doesn't demonstrate weird problems; if you would be unduly inconvenienced by a dead 12V auxiliary battery, then I suggest you replace the battery every three to four years if you live in very hot or very cold climates; and every four to five years if you live in an area with moderate climate.

An anecdote relevant to this:

2 weeks ago I went to the Toyota dealer (Watertown, MA) and changed the original Integrity tires on my 08 Prius (nearly 60k miles, but finally worn out). Bearing in mind what people here recommend, I told the guy there that I had been using 45 psi rear 50 front, had been getting high MPG (65-70 summer/55 winter), and wanted him to fill the new tires accordingly. I also railed a bit about being careful not to overfill the oil.

I drove away on my new Michelin Primacy tires (LRR, but otherwise a compromise between performance and mileage) and was expecting the usual hit from new tires on my mileage. I got it - MPG went from a bit above 70 on the MFD to around 66.

Being greedy, I went and checked the tire pressure - it was 60 in all tires! The ride was great - much less "hard" than the Integrities had been.

I couldn't believe it - so I went to the nearest service station with air and tested them again - same result. The sidewall says something like 44 psi. But the tires look and ride just fine.

So I'm driving with these tires - the rolling resistance is clearly slightly higher than the old Integrities (which had vanishingly low RR due to the near absence of tread at the end), the ride is great - yet whenever I check its still 60 psi.

MPG is still OK considering - my last tank has been worse (56), but it has been due to max AC and fully loaded driving at 70 MPH - not my habitual driving. And I'm still getting 66 when I drive right, with the tires showing absolutely no sign of trouble (yet).

I guess my point is that you can go up on the tire pressure quite a bit over the usual 32/34 - and somebody at Watertown Toyota seems to think that 60 is OK in a Michelin Primacy LRR tire.

I am not necessarily recommending this, and I think I will call the dealer to ask them if it makes sense.....it could have been an underling with a sense of misplaced humor who did it.

nice! it would be intersting to know if the tires are safe in all situations at this psi.

Drawing from 2 weeks experience, and a 120 mile trip today under maximal load (4 adults + furnishings for half a college dorm room), they have been excellent.

But you can bet that I'm going to ask them (and elsewhere) about it, especially before winter comes on.........