Yes I've read the "why don't I get EPA mileage" many times...mileage still stinks

On a Gen-II, the rear drum brakes can be adjusted too tight which will kill the mileage. If the same mechanic keeps adjusting them that way at every service call, it would lead to a chronic loss of mileage. Symptom #1 is if the car can't be made to coast.

Bill the Engineer

 

without some give and take with the op, this will be a tough one to solve.

 

All this brings up good discussion .
REGARLESS if OP is for real Or a troll, right......

 

i suppose it's possible to get a 'dud', as op said. certainly, there have been other posters with poor mpg's from the git go.

 

put it in neutral and see if you pick up speed when going downhill or when you're traveling along at 20-30 mph with your foot off the gas.

yes, the flux capacitor was a 'back to the future' reference.

the problem with the dealer is, they can't fix much unless the computer tells them what to look at.
also, even though the epa test returns 50 mpg, toyota considers 40 to be satisfactory.

there are many complaints here about low mpg, but no single issue causing it. if you want to attempt to find out what might be wrong, you'll have to spend some time here asking and answering questions. it's a fairly complicated process trying to fix things over the internet.

 

I don't try to get great gas milage. With our mix of short and long drives I get 41 mpg. I'm OK with that. We got 53 mpg the other day when we drove 90 miles to Tampa.

Also, I like cold air conditioning in this Florida summer heat. We are not young and can't take the heat like we used to. If that costs a few miles per gallon, I'm totally good with that.

I stay in the car while my wife shops sometimes. I watch inverter and battery temps with EngineLink HD for IPad.

 

Sorry OP for questioning whether your a troll or not.
It did bring out a lot more info from you.
But the thing that has me wondering , is your relationship with the dealerships.
It sounds like that they never had much hands on mechanical work done for you, when it comes to your issue.
It's sounds like they gave you some quick verbal answers , that were pretty general.
Other than that, I hope people can steer you in the right direction on PC.

 

Sometimes the flux capacitors can reproduce and cause major problems. Hahah, Bisco, you has me going.

Seriously, I think op needs to have car checked into a Indepentant Prius specialist mechanic, dealers don't know it all.

 

Is it still with original brakes? If it has and it has 109 t miles it really can’t be brake drag.
But 109 t miles in 8 years is about 14 t miles year. If you need to replace tires every other year its only 28 t miles per tires. Does this sound low to others? What sort of tire pressure are you using? I think most here use 42 psi front 40 psi back. Also it could be alignment problem.

 

If you are absolutely certain that it is not your driving habits, then how is the car mechanically?

What kind of tires do you have on it? What tire pressures do you run them at?

What kind of oil do you have in the car? What kind of oil filter do you use?

What kind of spark plugs do you run? Have they been changed out?

What about the PCV?

Alignment won't have much of an impact on fuel economy, but when was the last time it was done?

As everybody have stated, the 12v battery also has a huge impact on the car. Have you replaced it yet?

Since you replace tires every other year, the obvious question is: Why? Are they already worn out after 2 years? If so, then there is a major problem with alignment/suspension that needs to be looked at.

If there is somebody else nearby that also has a Prius in the same generation, I would do a coast and pulse and glide comparison. If you are stopping earlier than they are, then there is a brake problem on your Prius.

Post back so we can help you figure this thing out.

 

When you are traveling on a flat road or slight downgrade, look at the power distribution screen. As you slowly ease up on the accelerator, the power flow should change from flowing to the wheels to nothing before it changes to power flowing from the wheels back to the battery. By holding the accelerator pedal at a specific spot, you should be able to maintain it so that no power is flowing for more than just a moment. In this condition, the car is in free coast and will pick up speed on a good downgrade without power from the battery or engine. If you find that it is impossible to accomplish, you are getting too much drag from the brakes. Old fashioned mechanics were trained to set drum brakes so that the wheel when off of the ground only spins a couple of times before stopping. This is wrong for a Prius. The brakes should be set so that when the rear wheel is off of the ground, spinning it by hand makes it spin a long, long time.

Also make sure that your left foot is NEVER resting on the brake pedal. Just the weight of your foot will cause drag and kill mileage.

Bill the Engineer

 

This sounds like a good project for a Prius meet. 40mpg dropping to 30mpg when the car is not being used as a racer and eating tires are definitely indications that something (maybe several somethings) needs to be adjusted.

 

I think the op , hopefully has got some good info from some of the PC members.
Hopefully the op can find a solution. I doubt very seriously she will find an immediate remedy from someone on PC.
I say that because she has a deep seated issues . And so far it's anyone's guess.

 

32 hours since replying.

 

I took her seriously, I think , hehehe

 

what, the part about venting?

 

Yea man, hehehe

Her issue is a tough one to decipher .
I would suspect that she will need someone to go thru all major systems, or she got a dud.
This might be a case for detective Patrick Wong.

 

Actually, I'm right there with OP. Bought my 08 Gen2 in 2011 from a dealer (26k miles). Promised 50+MPG. Couldn't get it over 35 driving "normally." Joined this forum, read (didn't post, just read) about tip and suggestions. Started pulse/glide driving. Started slowing down. Started driving the speed limit (which actually really reduces the anger of traffic, so thanks for suggesting it). The problem is: I went from 34 average to 40-41 average. Dealer said it's my driving causing the problem.

Some oddities:

1) Since I bought it, it's had what I would call a valve tap. 3 dealers said it was fine and I shouldn't worry about it. They said the valves aren't adjustable (!) and when/if the engine dies, it can be replaced. This valve tap has gotten progressively worse.

2) I've gone through 3 12 volt batteries in that time period. All replaced by a dealer. I paid for them all (angrily, yes, I did think they were warranty but how many hours on the phone can you argue before you give up?).

3) The back pads (not shoes) were replaced around 50k miles and again around 160k miles. Front pads once at 140k miles. I did that myself so I could nose poke and make sure nothing was wrong (binding, corrosion, etc.). I do have a fair bit of mechanical aptitude. Nothing remarkable. Just worn brakes. I have seen reports of odd wear with the light usage of the pads, so maybe this isn't an oddity.

4) The gas engine (since I've owned it) has eaten oil. It's up to about a quart in 5k miles (the frequency I get it changed). I do realize it's a little crazy, but I keep it at the line (not over). So yes, every few weeks I'm adding a little oil. Every time I had a dealer change it, they told me the level was fine when it went in. Even when I told them it was low before I left the house, they would insist it was fine, nothing to see here.

5) Steering wheel buttons have never worked right. At the moment they're dead. I'm aware this is a common problem as these cars age, but I'm just mentioning it.

6) No matter what kind of tires I put on the car, the back tires cup in about 20k miles. I've gone through 5 sets of tires in the 170k I put on the car. I do realize that's not something I should necessarily complain about, but my last car (a Subaru Impreza) could go twice that before needing tires. Two rear tires so far have "developed" broken belts inside them. I used to work as a fleet mechanic and probably changed two or three hundred tires and only saw one broken belt in all that time. Two in one vehicle with different brand tires?! Dealer said I should be buying tires from them. Sigh.

Conclusion is that I'm pretty sure there's something fundamentally wrong with my Prius, and I wouldn't be surprised if there is something wrong with OPs too. I'm fairly confident that if I had a properly working Gen II next to mine, it wouldn't take long to find the problem (but I don't). As they get cheaper and cheaper on the used market, I might just buy one to do that though.... The dealers are simply OBD diagnosing. The mechanics are really nice guys, but they really lack the training necessary to properly troubleshoot an "advanced" problem.

My goal is to make this last until the Tesla Model 3 is out. If it doesn't, I'll just have to buy an X.

Jon