I've noticed many threads over the months that seem to indicate that as the Prius ages, it experiences lower MPG. I personnelly have experienced a decrease in mileage on my 05 model. With the advice of Prius Chat folks, the dealer, and even Toyota, no one seems to be able to explain the change. This makes me wonder if, as the hybrid system ages, does it lose 'something' which causes MPG to decrease? I haven't noticed that link made before and we as a community have not identified the problem or a solution for it. So could the normal aging process of the HSD cause lower MPG?
I have not seen these threads. Could you point them out. It seems to me that the loss of efficiency with high miles is fairly low in most cases. If you end up with bad cells then the numbers seem worse and that is to be expected.
I've noticed no drop. Reports of reduced fuel economy that I see typically have a reason: cold weather, changed driving conditions, mechanical problems, low tire pressure, etc. Not aging per se.
Are you talking about gainning MPG by replacing the 12V battery? Your 05 may need a new 12V lead acid if you are experiencing MPG drop even in the spring / summer. You can check the voltage in the MFD service menu. It is hidden so google how to get to it.
See here for discussion and procedure: http://priuschat.com/forums/newbie-forum/73400-weird-stuff-happening-mpgs-dropping-test-battery.html
What is your odometer reading? Have you seen following thread? http://priuschat.com/forums/gen-ii-...etime-mileage-report-japanese-hypermiler.html The 113k miles driven 6 years old Prius's FE is still improving year by year. As JimboK wrote, there should be some certain reasons to see reduced fuel economy. Ken@Japan
I've seen and read the threads other have mentioned, and I've run thru all the possible casues PriusChat members have suggested. The 12V battery is new and tests fine. All these things point to another possible cause, hence my questioning the HSD system. I guess there really is no answer, but I still find it baffling...... I guess if noone else is experiencing similar issues then I have a unique case and my theory doesn't fit. Thanks for eveyone's thoughts!
Has your commute changed in any way? What is your commute like? Perhaps traffic is getting worse slowly? How long has this drop been going on for? years? And just incase you haven't checked: Have you been keeping up with the maintenance? Cabin air filter? Engine air filter? Making sure oil isn't overfilled? Do you notice any leaking oil or anything under the car after you park it? What about your tire pressures - have you checked them recently? What about your tires? Any strange wear patterns? What tires are you running now? Does your main battery show massive swings in terms of charge level? Eg: full when you park it at night, nearly empty in the morning?
I have checked all those things countless times searching for an answer. The car has been back to the dealer for same and Toyota corporate sent a field tech to look at it without results. Yet I have lost 6 -7 mpg over the last two years. In retrospect, if it was the aging of the HSD, I guess more people would report the change. Nothing else has changed, the commute, tires, traffic, etc. Thanks again to all for your supportive comments.
Do you have a scangauge? Also, what kind of mileage bars are you getting in your commute (eg: 25 in the first 5, 50 in the 2nd bar, 20 in the 3rd bar)? What type of gas do you use?
It could be your gas. In the last week I've made 2 nearly identical trips to Dallas and back. The first trip, I got 40.1mpg according to my MFD. The second trip, I got 51.8mpg. The only change has been running 2 complete tanks of dino-fuel through the fuel system, instead of using crapohol. (Yes, I drive a lot) That's a 25% increase in mileage, just by changing to real gasoline. The difference amazes me. Chuck
We still don't know his odometer number. I traced his post. It seems less than 50k miles now. http://priuschat.com/forums/gen-ii-prius-main-forum/47187-how-many-miles-your-prius.html#post614766 His daily use is only 6 miles one-way. http://priuschat.com/forums/gen-ii-...-my-average-mpg-around-34-a-2.html#post475374 If we have to judge a real problem from the mpg number, it should be done on long driving after complete warming up. I bet his mpg variance is caused by other fuel usage factors, such as warming up fuel, A/C use and others, than for actual driving. Ken@Japan
My last three tank fulls have avg. 36 MPG. This is down from a solid 43-44 for the first two and a half years of ownership. I appreciate Bob's suggestions above, however, others have mentioned these as well, but these things have already been tried and eliminated. But I do appreciate the offers of assistance!!
Mine dropped 4 MPG since my last oil change. The dealer over filled my crankcase and let the air out of my tires. ARGH! I still can't get back up to 57-58. I am considering draining some oil out//what a pain. Also who would know if they put the oil in I gave them and if the oil I gave them was labled right? Too many varibles at this time and I will wait until the next oil change to see if it gets corrected. I am using 0w30 Mobil 1 so far ( at least that is what is says on the bottle). Also whoever sold us down the road on crapahol needs to be *********//what a rip off of the American people. PS// Time for a gear box fluid change.
A baffling case to be sure. +1 on ken1784's comments on the low daily trip mileage, ~6 mi. each way. The car would hardly be warmed up. Maybe the ICE would get to 157 degF. But I have read that a car must be driven some 20 miles for all the other mechanical bits -- wheel bearings and the like, even the tires -- to reach full operating temps. I'll take a stab; my three best guesses -- all the most likely ones have already been made: 1. The cause could be misalignment, front or more likely at the rear. In most cases misalignment would be suspected by tell-tale unusual tread wear or squirrelly handling at speed or in cross winds. I suspect however the short trips are also on suburban streets and not at speed. And the short distance travelled on cool tires may minimize any tread wear anomalies. 2. Is either the front or rear defroster on a timer? If not, the cause may be leaving either the front or rear defroster always on. Could be it was turned on during an infrequent spell of frost and forgotten. Doing so results in the ICE running continuously, especially noticeable when stopped, even though the ICE has exceeded the 110 degF trigger for shut down when stopped, or even the 157 degF fully warmed up condition. However, I would think this would have been noticed by now. 3. With as little daily mileage and fuel use, there would be relatively long periods when the stupid fuel bladder was only partially filled. I suppose that there is a chance that it has assumed a somewhat permanent "relaxed," low volume shape. If this were so, it would be reflected in repeated low volume fill-ups, say around 6 or 7 gallons. Evidence of this would be very low mileage for running through the first pip on the guess gauge. Hobba, are you measuring your MPG from the MFD, or are you calculating using actual fuel put in and miles travelled?
The best way to avoid trouble is to avoid trouble. When leaving my car for an oil change I give them three quart bottles of oil to use and put a big sign on the windshield: DO NOT TOP OFF OIL DO NOT ROTATE OR INFLATE TIRES DO NOT WASH I also tell the service writer that I'll check the oil level before driving away.
I understand the tires and the oil...but why not let them wash it? Can't imagine them messing up a car wash. Chuck
Alot of people/businesses are lazy and/or use horrible materials to wash your car with. The net effect is dings (maybe) and scratches (nearly always). I never let anyone else wash my car because everytime I do I end up with a scratch or spider webs from their crappy drying towels. A lot of harm can be done to the car's finish by a bad car wash. Some people don't care about that kind of stuff but I like my paint to stay perfect for as long as possible.
We're a bit OT (sorry OP) but I have to agree about the washing. I relented a couple of weeks ago because it was so cold and my car was so dirty, went through a car wash. The spinning brushes pulled the rear bumper panel out a bit. No permanent damage and easy to fix, but scary considering how bad it could have been. - D
