Help me get better mileage

:welcome: check your tire pressure and oil level. how many miles on the new tires? what brand and model? your friend probably has less freeway on his commute.

 

It sounds like you got 17" tires instead of 15" that come with the car, which will lower your mileage only a teeny bit (1 mpg...). Newer tires will give you a hit, but it sounds excessive. You probably got a tire that's not low rolling resistance. A low rolling resistance tire keeps moving more easily to preserve momentum, and thus the car works less. You may not be able to do anything about it other than get new tires, but that price would outweigh any mileage gains.

Search on this forum or google for Prius tires, lots of people have talked about it. A popular choice seems to be Goodyear Assurance Fuel Max.

For other mileage techniques, given the speed you travel typically, you should learn about warp stealth, a no-fuel mode over 42 mph that keeps the engine going at minimal RPM. It's very good for downhills or when your exit is coming up and you have to slow gradually anyway. Scroll down on this page: Pulse and Glide plus Warp Stealth in the Prius II for maximum FE … - CleanMPG Forums

 

as long as it's not above the full line your fine. higher pressure will reduce traction a bit. maybe go up a few pounds? it might just be the type of tire as mike says above. also, it's possible your 12v battery is going bad. how many miles on the new tires? there is a break in period.

 

Synthetic oil should get you higher mpg, that seems odd. He must have meant 3.9 quarts probably. If you got that at the same time as the tires, it's tough to know which variable did it, but maybe it's slightly overfilled(?), which would account for reduced mpg. It may actually be a little much, like bisco said, shouldn't be over top dot, and most say on a Prius it should be slightly below top dot of dipstick.

Air pressure best thing to check first before getting dirty/paying someone to check on anything. Rain and snow and everything in between this winter, I was fine at 41 front psi/39 rear psi, I wouldn't worry about slightly higher psi and traction.

 

air filter! good point, that's another thing. warm the car up, 20 min. or more of driving, park on a level spot, shut it off and let it sit for 5 minutes for the oil to drain down. check the level by pulling out the dipstick (careful it's hot!) wipe it with a clean rag and insert and remove and note the oil level. you may need the right lighting or something behind it to see new oil properly. you can check it cold too, it's just drained downn a little more and will read a bit higher. there is a battery check in the mfd, you can search for it or someone will post the link to the thread.

 

The old, smaller tires were going around more times per mile. Car doesn't know how far you went, just counts revolutions at an assumed tire size.

Try finding the rev/mile for your new tires and the old tires (tirerack?).

Then adjust reported miles by by oldrevs/newrevs.

 

Thanks Stoods, you'll find some others on here are able to do better...

Although you'll likely find all the answers by the time I'm done, I'm working on a post for "normal" drivers to try all the little mileage tricks in their daily routine while still going with traffic. Plenty of other people have done this, especially for newer model Prii, but I've found at work there's a bunch of people with Prii who, like me, have little background in cars but, unlike me, don't have the time to sit down and read the entire internet to figure the Prius thing out I'll send you the link when I finish.

 

It's the tires. There is a combination of three factors.

1. New tires. (they often give a few percent reduction in MPG while they "break in")

2. If the rolling circumference is a little larger than stock then it gives a lower indicated MPG.

3. The larger wheels on the touring edition are more aimed towards performance tires instead of LRR tires. I think they've sold you performance tires without any regard to LRR (low rolling resistance). LRR is important to the Priuses overall efficiency.

Note that "2" is not a real MPG drop, just an indicated drop based on incorrect odo calibration. But unless they've sold you a grossly oversized tire it shouldn't be more than 1 or 2 percent. Reason "3" will account for most of your MPG drop.

BTW. That story is VERY common here "New tires and then big MPG drop".

It's really worthwhile investigating what LRR tires are available in your wheel size. Search the forums here and you'll find some recommended LRR tires. A few that come to mind are :

Bridgestone Ecopia EP100 (Very Low Resistance)
Bridgestone Ecopia EP422 (All Weather)
Hankook Optimo H418
Michelin Energy Saver A/S
Michelin Primacy MXV4

That's not meant to be a full list, just a few to get you started. I think the Michelins are good but pricey, the Hankooks are good value and the EP100 are mid priced and very low rolling resistance.

 

If you're stuck with the tires just ride on them. Inflating to max sidewall pressure should improve the handling. On my Gen2 the Integrities were a bit squirrelly on dry pavement at 45psi. (The yellow idiot light would flash during a stop.) On wet pavement no idiot light.

Didn't the Touring have 16" wheels?

Check the 12v battery voltage on the MFD in Maintenance Mode. Just do a search. If it is the original you are due.

 

OP, please do get back to us on this, including the exact size of these new tires.

Even if you replaced the tires w/the exact same model and size, you will likely see a bit of mileage drop, at least initially. See Tire Tech Information - Tire Rolling Resistance Part 3: Changes to Expect When Switching from Worn-Out to New Tires.

http://priuschat.com/forums/newbie-forum/73400-weird-stuff-happening-mpgs-dropping-test-battery.htm

I'd suggest you check it after the car's been sitting many hours or overnight.

 

First off, post the exact brand/model/size of the tires (eg "Falken Ziex ZE 205/55/R17" for example) so we can stop guessing.

If you need to change them then they should at least give a prorated refund/trade on the existing tires.

As for whether or not it's worth doing. Take a conservative estimate of 44 MPG (after they're broken in) versus 48 MPG over an estimated 45000 mile tire life. Do the math and it comes out at over $300.00 saving (more if fuel prices keep rising like i think they will).

BTW. That's conservative because you can probably do even better than 48 MPG with the right LRR tires. If you want to get over 50 MPG then definitely see if you can get something like the EP100's or EP422's in your wheels size.

 

Yeah that sounds right. They're 16" wheels (not 17") as JimN pointed out above.

The rolling circumference is 1.7% to 1.8% larger than stock so that only accounts for about 1 MPG (comparatively you're really doing about 1 MPG better than indicated). Also tread-depth probably accounts for another 1% change in circumference, so in total that's about 1.5 MPG indicated difference.

Also you'll probably pull back another 1 to 2 MPG as the tires break in over the first 5 to 10 k miles. They are probably good all weather tires but perhaps not strictly LRR.

 

That's good. Those tires can't be too bad then. You might even get another couple of MPG out of them after they break in some more.

Yeah the car has to be as level as possible to get a good reading. Also the car should have been turned off for long enough for all the oil to drain back to get an accurate level. Wait at least 15 minutes, longer if possible. Also remember to wipe the dipstick first and then re-insert it to get a good reading.