PRIUS GAS MILEAGE SUCKS

Regarding your fuel economy issue: I'd suggest that you Check your engine's air filter for dirt and debris. And make sure you're doing oil changes 2K - 10K miles.

 

<div class='quotetop'>QUOTE(westex39 @ Aug 19 2007, 05:39 PM) [snapback]498829[/snapback]</div>

The cornerstone for getting high mileage in the Prius is length of trip. A lot of short trips will give you in the high-30s. During the first five minutes of using the car, the engine is warming up and the mileage is poor. The first thing you must do if you want higher mileage is to take longer trips, 10-15 minutes.

Another thing you mention is that you 'keep up with traffic'. This is generally a bad thing in the Prius. Most drivers do not drive efficiently, so you either want to drive a little faster than traffic or hang back from it.

Finally, you'll find mentioned here the idea of 'pulse and glide'. Most people think that to get good gas mileage in a car, you have to drive slowly, and accelerate slowly. In the Prius, the opposite is true. Pulse and glide means to get up to speed as quickly as possible and then use the accelerator minimally to maintain your speed. You probably noticed that on your computer screen that once you get up to speed, you get 60-100 MPG routinely, but poor MPG whenever you touch the accelerator. Consider this scenario:

Two cars are driving 2 miles after a stoplight to get to the same destination. Car A will use a slow, gradual acceleration to get up to speed, Car B will use the accelerator to get up to the maximum speed as quickly as possible and then use the accelerator minimally after reaching the speed limit. The speed limit is 35.

Car A takes 30 seconds to reach the speed limit. It gets 25 MPG while using the accelerator for 30 seconds, with 80 MPG for the rest of the trip 5 minute trip.

Car B takes 15 seconds to reach the speed limit. It gets 20 MPG while using the accelerator for 15 seconds, with 80 MPG for the rest of the trip 5 minute trip.

As you can see, Car B halved the amount of time using the accelerator, but it only saw an 8% reduction in efficiency during its acceleration. It also spent 15 more seconds getting 80 MPG as opposed to 25 MPG.

So in conclusion, if you want to increase your MPG take longer trips, don't match what the traffic in front of you is doing (and hang back if they are going at a speed that is causing you to constantly use the accelerator), and get up to speed as quickly as possible.

I advise watching your screen a little bit to see where your MPG is at any moment. None of this is hard to figure out if you watch the screen and think about what you are seeing on it in relation to how you are driving.

 

A lead foot on the accelerator and a feather on the brakes seems to work for me. As gippah said, don't mess about getting up to speed then use the lightest of throttle. If you know a light will be red when you get to it lift your foot off the accelerator now and brake softly all the way to the light, it will likely change to green before you get to it.

 

I just filled up for the first time. I have no idea ho to really drive the thing yet but I averaged 48.3 mpg. I'm giddy! I can't wait til I actually know what I'm doing!

 

Hmm.. I live in Northwest ohio where it is completely flat and I average around 47-50 MPG Highway and 43-45 MPG city... so go figure... although I never understood how the EPA figured that the prius gets better city mileage than highway mileage... I can take a 500 mile roadtio down to Clarksville, TN from here and average 54MPG yet around town I only get 43-46 mpg... I guess I live in too small of a town?

 

A lot of you folks are sure being presumptuous here. Like Toyota couldn't make a lemon or something? Must be user error, right? Not all Prius are equal.

Sure, his 38 MPG could be in-part due to driving behavior, but it still sucks and so does the 42 MPG that I average with mine. And, yes, I know all the tricks and have been driving it for a while now. I can get into the mid 60s with my friend's Prius. Mine is simply a dud.

The real question here is if anyone has any success in getting a Toyota dealership to help when they have sold a relative lemon to poor suckers like us? Isn't there anything they could reset or test beyond checking alignment and tire pressure? Surely, something is not working up to spec.

Please, no more preaching on how much better 38 MPG is than a 1/2 ton truck. People in our position are looking to improve our gas mileage, not learn to appreciate sub-par performance from a $21,000+ investment.

 

It helps if you could provide more info why you think your Prius is a dud. What are your driving habits? Tire Pressure? Maintenance intervals? Commute length/terrain? Did you swap with your friend for a few hours or the duration of a tank of gas? 42MPG ain't bad for driving it like a normal car.

 

Since you reopened this discussion I'd like to throw out another not-thus-far-discussed factor. The fuel bladder. The OP stated that he got 38 mpg on the last tank. Ding!!!

There is no way to guage the true fuel economy on a single tank simply because the fuel bladder is so variable. The fuel economy numbers are really only valid after a good long period of time like 6 months or 2 yrs. The reason is that if the bladder causes the pump to shut off early on the tank before last there may have been only 9 gal in that 'FULL' tank. Thus when the fuel light came on to fill up on this tank one might have driven only 380 miles but due to bladder variability the tank might have taken 10 gal on this one.

That appears to be 38 mpg but in fact it's about 47-53.

 

Like I said, I'm not new to this. It is a dud. I switched cars with my friend for a week. He had no idea that his car could get such good gas mileage. Our dealer has an overly aggressive maintenance program that I've stuck to to the date and even pay for my own oil so I could upgrade to synthetic. Tires are 42/40 nitrogen filled. I coast like you wouldn't believe , get up to speed relatively quickly, go the speed limit, don't run air unless really needed, run the tank until almost empty before filling, keep the car empty of excess stuff and all the other fun stuff we all learn. I have 16,000 miles on the car. I could teach classes on getting the most out of a Prius. My commute is 20 miles in hot weather on moderate terain with relatively few stops. The way I drive, I should be in the 60s or very least high 50s, not 42. Trust me, it's a dud. Dealer offers no help at all.

 

You do have to change your driving habits. I would check out some of the responses in prius chat to improve your mileage. If this doesn't work I would contact your Toyota dealer. I have a 2006, with 28000 and currently averaging 51mpg. I don't drive slow but don't do jack rabbit starts, coast as much as possible to a light or stop, could speed for me on interstate is 64.

 

ok.. I have to throw my two cent in here.. We bought our Prius just over two years ago. We were thrilled with the mileage, but still a little bummed it didn't get the 60mpg epa rating (truthfully, we'd read enough to know that wouldn't happen). About two months ago, I took it in for oil change and the service guy asked about mileage.. I complained that it "sucked" (for a Prius) at 37.5 mpg. He gave me a huge article on how to drive a hybrid and reset the mpg mileage.. Since then our average has gone up, no kidding, from 37.5 to 57.5. Granted, it's warmer.. but still, that's a HUGE increase.

For us, it is DEFINATELY how we drive.

 

huge article? scan + post it here?

 

sorry... read it and passed it on to a neighbor who drives a prius... It was very technical, but basically talked about pulse and glide, etc...

 

This is how we've always felt about our Prius mileagewise. A "dud". Our best tank ever was maybe 45MPG, and my fiance used to P&G too. She doesn't even bother anymore.

Dealer won't do anything, its not a quantifiable issue. I don't really expect them to.

 

If it's really a "dud" then there has to be a way to trace all that lost energy. Having a known good car to compare to is a great asset. First I would recommend a glide test, i.e. start at point A with a known speed in each car and see how fast you are traveling at point B, which should be sufficiently far that you drop at least ~25% or so. That will tell you if there's some kind of drag that shouldn't be there. A positive result should get you looking far something like a sticking brake caliper/shoe. If one wheel is much hotter than the others after a high-speed drive, there's your fuel-sucking parasite. Honestly, that's your most likely suspect.

I suppose a fault in the drive train is possible but extremely unlikely. That's not Toyota fanboyism talking, just the fact that something that badly amiss should set a code. Too much fuel, faulty spark, bad o2 sensor, etc. ought to be caught by engine management. Problems with the hybrid system would manifest a light show eventually, too, and you would probably see flaky battery behavior. One possibility you might consider is to reset everything by disconnecting the 12V battery for ~15 minutes, which would cause the computers to re-learn the fuel trims and other parameters.

If you're serious about tackling it, I suggest posting a dedicated thread in the Technical section with all the relevant info (including your experience with a different car). I'd love to see the experts help you hammer this thing out. I would trust input from this place long before trusting a random dealer service department, anyway. A few techs that are worth their salt (and more) do hang around from time to time.

 

I usually get 51 mpg back and forth to work in DC. Today on the way home I chose to intentionally drive slower with the A/C off. I drove no faster than 60, except when zipping down a hill to get speed for the other side (still showing 300 mpg on the scan gage).

I got four 5 minute sector bars on my MFD that were at least 65 mpg before I broke down and turned the A/C on.

It can be done.

 

To paraphrase a diagnosis from the IT crowd, I believe the DTC in Question is:

DTC111: Problem exists between seat and steering wheel.

As F8L mentioned in the original thread, take a minute to calculate the actual difference in fuel used at 15,000 miles per year at todays average price of $4.04.

Westex39 Prius: 38 mpg = 395 gallons or $1,595/yr
Not_Amused: 42 mpg = 357 gallons or $1,442/yr
EPA: 46mpg = 326 gallons or $1,318/yr

Westex39 Pickup: 16 mpg = 937 gallons or $3,786 per year.

Westtex, I'm sorry you're only saving $2,191 per year, not the $2,468 the EPA said you should be. I'd write to them and ask for your $277.

Not_Amused, looks like someone owes you $124!

Or you guys could take a little personal responsibility.

There are two main possibilities, there's something wrong with the car or there's something wrong with the driver. In the first case, its usually something simple. Wrong tires, wrong inflation, sticky brake dragging, windows down on highway, AC blasting on high all the time, etc. If there were anything seriously wrong, it would be difficult for it not to be throwing any sort of codes. In the second case, you have to be willing to admit that the problem could be you. Regardless of how skilled you are at driving conventional vehicles, this is a completely new animal. If you want to drive it well you have to understand it, and understand how to get it to do what you want. Most peoples preconceived notions about how to drive the Prius efficiently are completely wrong. As far as the EPA numbers, they runs the cars through a standard cycle. The original cycle was very optimistic, and was about the best you could do under ideal circumstances. The new cycle is meant to better represent how people actually drive. Still, if you don't drive the same way the computer does you won't get the same numbers.

Beyond that, there are circumstances that will just never allow you to get really stellar mileage. If you have to make lots of short trips, with long breaks in between, the engine will spend a lot of time in its warmup cycle. Same thing in cold weather if you don't use a grill block and maybe even a block heater. Really hot temps can also be detrimental if the AC is always blasting, and never has a chance to throttle back once the car is cooled down. None of these issues are unique to the prius, all vehicles suffer from them to some degree. The prius may be somewhat more sensitive to these issue, but will still generally get much better mileage than any other similarly sized vehicle under the same conditions.

You could be right, after all that there really could be something major wrong with your car. Showing up at the dealer and yelling at them about how much this car sucks probably isn't going to incline them to want to help you much. For that matter, doing the same thing on this forum probably isn't going to incline people to want to help you much. Ideally you'd get someone from the dealer or from this list who knows how to drive the Prius well to drive your car and see what they can do. From stories here, we know its not uncommon for people to bring their car to the dealer claiming there is something wrong with it that it can't achieve good mileage. The tech will then take it home overnight, and bring it back showing what the car is capable of doing. I think that is a big part of the reason people here tend to be pretty skeptical when someone comes in making these kind of claims. Particularly when they're rude about it.

I will say that part of the problem lies with how we calculate fuel economy in this country. It exaggerates the small differences at higher efficiency, while trivializing very real differences at low efficiency. If we calculated the actual fuel consumption as they do else where:

10mpg = 10 gal/100 miles
15mpg = 6.67 gal/100 miles
20mpg = 5 gal/100 miles
25mpg = 4 gal/100 miles
30mpg = 3.33 gal/100 miles
35mpg = 2.86 gal/100 miles
40mpg = 2.5 gal/100 miles
45mpg = 2.22 gal/100 miles
50mpg = 2 gal/100 miles
55mpg = 1.81 gal/100 miles
60mpg = 1.67 gal/100 miles

While I'm the first to admit I'm pretty bummed when I come in under 50mpg, and really happy when I can push over 60mpg the reality is it doesn't matter that much. I enjoy the personal challenge of it, but its affect on my wallet is minimal. At least its an improvement over the old personal challenge I used to enjoy, seeing just how fast I could get off the line and up to speed limit + 10

Rob

 

No mention of oil level above, check your oil level is at least 6mm or 1/4 inch below the full mark on the dipstick and that the dipstick is going all the way in when you check it. You say you coast like you wouldn't believe so we know there isn't excess drag when the engine isn't part of the equation so lets look at what your engine is doing. If you were not able to coast I'd say check the rear brake adjustment as many mechanics like a nice tight park brake it may be over adjusted but I doubt this is the issue.
If your speeds are often above 65mph this may also account for high consumption, please excuse me if you have already said they are not, I haven't re-ready all posts. I drive between 65 and 75 on the open road and accept that my consumption will be higher than in the city.

I'd not bother with nitrogen in the tyres and worry more about what tyres you have on the car, they are factory standard I assume?
Have you reset you average consumption? It's easier to see improvement if you reset each tank, 400 miles on an average over 60,000 miles won't show much or any change no matter how you drive.

Sorry if my post is going over stuff previously discussed.

 

Make sure your tire pressures are at least 35/33 specs. 38/36 might be better.
Lighten up on the accelerator when you are going downhill.

 

We've done it all, our car is just not capable of achieving mileage like that.

Really, we don't care. I'm just saying Not_Amused isn't alone in his feelings about having a "dud".