Chasing a "poor MPG" problem, possible excessive drag on front wheels?

39mpg and 45mpg are very close to each other... Boosting your tire pressure up a few PSI at a time until you notice less traction and then reducing a few PSI will help you find the max MPG. My preference is 47psi in front and 45psi in back in Summer and lower than that in winter.

But too often people buy the wrong tires for Prius and get sold "safer" high traction tires instead of Low Rolling Resistant (LRR) tires, which could easily be your only problem.

But in general this cold time of year on short trips around town your MPG is normal... The true MPG test is a long freeway drive in 75' to 85' Summer weather with Summer Gas blend and no wind and no stopping. I usually get 52mpg at that point with my Prius on trips to California, but 39mpg in coldest parts of winter driving around town is fairly common.

Anyways, welcome to PriusChat. I live a little more than an hour north of you if you ever need help with diagnosis, spare parts, a battery pack or just want to be friends.

 

If your problem really was excessive drag, the energy would manifest itself somewhere as heat. You would probably smell or hear something abnormal if that were the case. I think it's more likely that you're not burning fuel efficiently.

 

Your pics, videos and links are limited until you have enough participation. This is to protect PriusChat from Spammers.

Just spend some time reading and commenting on here and by the end of the day or soon after that restriction on your account will go away.

 

I've been here over a year, and I still can't post much.

 

My Gen 2's gas mileage went up after I took off the rear brake drums and dumped out all the dust that had been circulating around in there.

Are you in neutral when you turn the front wheels by hand, or is the other wheel moving in the opposite direction?

Maybe it's time to change the transaxle fluid - but I wouldn't expect that to buy you that much.

 

I didn't see your video the first time I read this thread (empty box). Now that I can see it, it does look like you're having to fight it to turn the wheel a bit more than normal. I don't know if you'd want to undo the axle nuts, but it's common for some mechanics to tighten them with an impact wrench rather than a proper torque wrench. If those were overtightened, I don't know if you can just back them off and torque them to the proper torque as I don't know what that would have done to your wheel bearings.

Depending on where you live, and how you drive, Prii can be pretty easy in the brakes. My Gen 2 had well over 200K miles and while I did the front bearings a couple times, there was still plenty of pad left - on both the front as well as the rear. If you're in a high corrosion area, I suppose you could get some rust buildup underneath the pads which makes your wheels harder to turn.

I ended up doing the rear on my Gen 2 only because I developed a slight leak on one of the slave cylinders. I don't know how that happened, but it was squealing just a little bit and I was trying to sell the car, so I ended up doing a complete brake job on the rear. That's when I noticed there was a bit of brake dust and road dust circulating around in the rear brake drums. After doing the rear brakes I noticed about 5 more MPG.

For the transaxle fluid, I wouldn't use anything but the Toyota WS stuff. I got a funnel and attached it to some clear tubing I got at the hardware store so I could feed that into the fill hole from the top. Unless you've got some other arrangement that works, that's the only way I know to get the fluid into the transaxle rather than all over the floor.

 

There's no way to free-wheel the front axle, because it's connected directly to the gas engine and the electric motor through a planetary differential at all times. There is no clutch and there is no actual neutral. If you could turn the drive wheels, it would have to rotate the electric motor. Difficult to do without considerable drag.