I bought my Prius about 6 months ago, and when I first got it was getting 42mpg, and now it has dropped off to about 30mpg. It seemed like the transition to poorer mileage happened fairly quickly, about 2 or 3 months ago. I could really use some help troubleshooting this, haven't been able to pinpoint it yet. Some info on my Prius: 2007 110,000 miles Has some Michelin all-season tires. I can check the exact model Things I have tried: Replaced the 12V battery. Old one was a Optima battery, put a brand new Optima in. Tires are 40psi in the front 38psi in the back Oil is 2/3 full Monitoring driving style, avoiding excessive breaking, fast acceleration Checked if the front breaks are dragging with finger test. Seemed like they aren't Things I haven't tried, but plan on soon: Wheel alignment. Doesn't seem off or anything when driving, but when we got a pair of tires put on, they said it needs alignment. Check if the emergency break is dragging Some clues? Mileage dropped off fairly soon after we put on a pair of new all-season tires on the back. However immediately after the new tires we did a road trip and got 50mpg. I think as soon as we got back to the city we started getting around 30mpg range. Battery level indicator very rarely drops below 50%, seems to hover around 75% most of the time. Not sure if this is normal. Mileage dropped off around the time weather got colder, maybe it's just that we're running the heater a lot, and doing short trips? We live in Vancouver BC, and it's been around freezing for a while now. It seems like we're not getting as much power going up hills etc, but it's hard to tell. A rear brake light burned out and a headlight burned out since problems started, making me wonder if there's something funky going on electrically. Could easily be coincedence though. I'm a bit suspicious there's something wrong with the traction battery, but that's an expensive fix, so hoping not. I've calculated the MPG manually after fillup, and using the built in monitor, works out to about the same. Thank you very much for any insight.
Do you think that accounts fully for the drop in mileage? Seems like a 30% drop in mileage is very drastic. Also, we were getting 40-42mpg with the short trips before.
I second JC's assessment. Short trips are a mileage killer in the Prius, doubly so in cold winter weather. When Prius first starts up it runs in a deliberately inefficient mode until the engine heats up to around 140F in order to reduce emissions. Short trip means less time for it to heat up, winter weather means it's starting from a colder point. Also, if you have the HID headlights (if your car has fog lights, the headlights are HIDs) then it's a known problem on the Gen 2 Prii that those burn out often. You can get the replacement bulb on Amazon or eBay for around $40-$50 and there's numerous videos on YouTube to show you how to do the replacement yourself... Though it's a bit of an annoying process, and you should watch out for counterfeit bulbs when purchasing... They'll die on you much more quickly.
If there were something wrong, you wouldn't get 50mpg on a long road trip. When your heater is on, the engine will run non stop for a while. So on a short trip, it basically never stops. Like a short trip in a Corolla, getting 30mpg
JC91006: I should be clear that we got the 50mpg on the highway after we put on the new tires, but immediately before I noticed poor mileage in the city. So I think it's possible that something went wrong after the highway trip and before poor city mileage. On the other hand it does seem reasonable that all this can easily be explained by the short (often 10mins or less) trips, cold weather and running the heater. Bisco: I think so, but I don't really know. I've never paid a lot of attention to what gas I'm putting in the car aside from choosing the low-octane kind. Kate: Thanks for the lightbulb tips. Gahd those are expensive. Thanks for your input so far! I really appreciate it!
This is a trick I picked up elsewhere on this site... During the winter I pick up a couple of pieces of cheap 1/2 inch pipe insulation at the Lowe's down the street (Shop Frost King 1/2-in x 6-ft Foam Plumbing Tubular Pipe Insulation at Lowes.com), cut em' in half lengthwise and cut notches in em' to match the Prius' front grill then use them to make a front grill guard like this: If you make shorter trips pretty exclusively you should consider doing so as well... But remember to remove at least the bottom-grill pieces for any longer trips you make if you do!
I've been getting better mileage lately, almost 35mpg. I haven't quite been scientific enough to determine exactly what helped, but I think it was down to the pipe instulation on the grill (for the cold weather) like Kate Harvest suggested, slightly warmer weather, bumped up the tire pressure, and a few longer drives. I'll be keeping an eye on things, but I think i can conclude that my prius is behaving normally. Thanks for everyone's help.
Has the transaxle ATF ever been changed? If not It needs to be done. Benifits: The car hill be happier, run smoother, and pick up some mpgs. I picked up the 4 mpgs I lost after waiting 100K to do mine.
Not sure if the transaxle ATF has been changed, I'll check into that. That's the transmission fluid right? Is that something scheduled for 100k miles? We just hit that recently.
Yes, that is correct. ATF = Automatic Transmission Fluid, although the Prius' eCVT is a transmission system, it is not an automatic transmission mechanically as one would normally understand it. Be sure to use genuine Toyota ATF-WS, OR, if you want to use an alternative, be very sure that whatever you use instead is the equivalent. A couple of other members use something else, and in one case is more expensive than Toyota ATF-WS, but that member believes the one he uses to be superior. It actually is not in the normal service schedule as Toyota market the eCVT ATF to be a "lifetime" factory fill. However, some members, who have done oil analysis of their used ATF-WS, believe there to be benefit of changing the ATF first at 30,000 mi and thereafter every 60,000 mi. YMMV and it is your car so you decide when, or even if, to do it. In your case, I would do it as soon as is practical for you and then every 60.000 mi thereafter. In relation to the thread topic, if you are chasing MPG, I don't believe changing the ATF will add any significant MPG. I could be wrong, and I'm sure any others will chime in to correct me, if I am.
take a look at your spark plugs. I bought my 04 a few months ago with 140,000 miles. Vin number had no record of the spark plugs being changed so I decided to check and have a friend confirm that they needed replacing. Ended up going with the Bosch Iridium tips at Auto Zone for ~30$. Car is happier to sit in the 50-75 mpg range as opposed to 25-50 with the old spark plugs. The computer is still averaging the milage lower than I think it actually is, but we'll see once I add the data to my spreadsheet. New spark plugs may not be the case for you, but they're suposed to be replaced every 120-140 thousand miles, and considering its a 30$ fix, I think it's worth it.
