something's not right

Mr. Farmer, when I drive my Prius in town I have gotten anywhere from 50-57 depending on the commute. I do try to get good MPG - not driving slow, but driving as directed here. I accelerate quickly up to 5 mph over posted limit then release the gas, then lightly apply the gas again just barely enough to maintain speed. I will also accelerate quickly up hills, and just before the top let off the gas and coast over the crest. On the way down just a little application of throttle to slowly build speed for the next hill. This is NOT slow driving, but it IS a change in driving habits. It's neither difficult nor boring. It actually is fun leaving everyone behind at the stop lights and (on my current tank) still getting 50.6 mpg.

On the highway, I used to commute the worst possible route for mileage in the Prius. A tollroad that would go from 75-80 down to stop-and-go at the drop of a hat. I drove the car lightly and over the year I had that commute got never lower than 46.5 on a tank. It think I probably averaged 48 for the year.

NOW & HOWEVER...

When the wife drives the car on her in-town commute... 43.5. If I reduced the tire inflation to just below stock like yours is, likely she would have dipped below 40 easily. She does not drive in a crazy manner, however, her methods of driving are just very bad for gas mileage. She will accelerate quickly off the line, but then does not let off. She just keeps letting off pressure as she gets to the speed limit. But the important point is HER FOOT IS ALWAYS PUTTING A GOOD AMOUNT OF PRESSURE ON THE GAS PEDAL. Then she only lets off the gas at the last minute and begins a moderately hard braking action (instead of coasting up to the light if possible).

The way I drive the Prius, no one riding with me can tell I'm doing anything special. When my wife drives, no one ever thinks she's driving too fast or hard or unsafe.

You have years of bad MPG driving habits you didn't even know you had. It's not JUST about speed. It's about putting your brain between you and the car. It's not hard, and once you get used to it you won't give it a second thought.

Also, I have to ask, are you getting your Prius MPG numbers off the Prius display screen, or are you calculating it by hand? I assume you've noticed there are two different screens, ENERGY and CONSUMPTION. Calculating the Prius mileage by hand will give you wild numbers since the amount of gas you can get in the tank at any given fillup is variable. See posts on this forum about the Prius gas tank bladder and why that is.

Also remember that if you got only 2 mpg off the EPA numbers on a previous vehicle, remember that when you take that as a percentage it plays havoc with the higher numbers on the Prius. That is, airing up your tires to 40 psi on the Prius can get you 3-4 mpg better. It's hardly noticable on another vehicle that gets less than 18 mpg. *In the Prius, sneezing can change your gas mileage 3-4 mpg*

Another thing: try some Shell gas or switch brands. And NEVER use anything but 87/regular unleaded. If you go up to 89 or 92 it will KILL your mileage.

Don't give up. You've got at least your self-prescribed year to get better mpg.

 

Sorry - not buying that one.

... Brad

 

"B" is to avoid riding the brakes on a long downgrade. Not an issue here, I gather.

One thing you might try is to keep an eye on the "Consumption" display while driving for the next few months. You might find the MPGs improving as if by magic... good luck!

 

I think there's a semantic issue that gets in the way of explaining what gives good mpg and what doesn't. Its the word "fast". I drive typically 5 or 10 miles over the speed limit - that's 70 or 75, and have a 25 mile commute each day. I get 49 mpg. Why? Driving fast isn't as harmful as driving agressive is. If you are going to drive like you are on a NASCAR track you are going to get crummy gas mileage. Someone in England tested running a Prius on a track with the gas floored the whole time and got like 18mpg with it. However, that's not a problem with the car. That's a problem that exists between the steering wheel and the seat.

 

I started to write a post to mfarmer1, but then desided to write it to the other members of PC who, in good faith, tried to respond to a request for help. Some people don't really want help they just want the attention. It's amazing how the EPA numbers have been qouted several times, but it was never noticed that the Prius' EPA ratings old or new where higher for city than for highway, first clue that the Prius may be a little different. And bragging about not taking time to read an owners manual, and the bit with the diving gear; it's been awhile since I've seen someone try so hard to prove their ignorance. I thought prehaps if we could get past the hostilities, that maybe we could still help, perhaps even prevent a heart attack, but obiously, Type A here is too busy checking themselves for hemoroids to realize that. And just to make it clear, these are my opinions only and are not intended to represent any other PC member. I have found that the members of PC are more than winning to take their time to try and help another member, newbie or senior. I belonged to a number of forums over the years but none with so much synergy. Mfarmer1 doesn't have time to read the owners manual, I wonder if there's time to look up the word "narcissism"?
P.S. Sorry! I hit post when I meant to hit preview. I just wanted to add that we will still be here whether mfarmer1 would actually like help or just wants to continue with the diatribe. Venting allpwed, but usually delays getting to the source of the problem.

 

Well said. The way you use the throttle in this car for best gas mileage is counterintuitive to other vehicles. The way the throttle responds amounts to a "hysteresis" effect, it is directional dependent. My wife and I both started out the first few miles using the throttle incorrectly. Once we learned to lift off and get back into it slightly our mileage shot up. (First mine, then hers when I explained the technique and she adopted it.)

Thanks, I suspected as much.

 

Really, I think the 1,200 miles may be a big part of the problem. That, along with the fact you are calculating mileage by dividing gallons into miles. This very standard way of calculating mileage just doesn't work well with the Prius -- at least not until you've filled MANY tanks. The reason is the bladder inside the Prius's fuel tank. It often restricts how much you put in, so that some days you'll be able to put in only 8 gallons, while on others you could put in 10 gallons. This obviously affects your calculation of gas mileage. My calculated MPGs go up and down each time I fill. Here is a stretch I had about one year ago (calculated MPGs): 54, 47, 70, 41.

If you keep track of mileage on the MFD (the Multi-Function Display), then you'll have a much better handle of your mileage. The same four tanks above showed more consistent numbers using the MFD: 50, 52, 53, 50. Have you kept track of this information, as well?

I've had my car for just over one year. I drove it the way I always drove cars when I first got it, and I got great mileage. (This may be hard for you to believe, but I am not an aggressive driver.) My first few tanks were over (barely) 50 MPG. Now, I still live in the same locale, but my past several tanks have been right around 60 MPG. That's a nearly 10 MPG increase and it comes from knowing more about driving the car, but also from having the car break-in.

You don't have to have any particular political or societal view to have success with this car. You don't even have to drive it in a "reasonable" fashion. If you have driven the car enough to get four tanks of gas, and you still are not showing even one tank above 40, then I think you need to have the car checked out. Unless you drive only a few minutes at time, or never get the engine warmed up, you will not get consistent MPGs in the 30s.

Look at GreenHybrid.com. There are 1,708 users who report each tank of gas they buy for their Priuses. This may be a self-selecting group, but it still is a valid sample size. One half of this group report their mileage to be between 44.9 and 50.4 MPG. The standard deviation is 5.1, with the median and mean mileages at 47.6 and 47.5 MPG, respectively.

Not looking for a convert, here! I'm just hoping to help you figure out what is going on.

 

I drive every week to Thousand Oaks from San Diego, 5 to 134 to 101. The minimum I get on my 08 Package 6, 5000 miles on it has been 44mpg. I just drove home last night and hit the driveway at 55 mpg. That was at cruise control set at 65. At one time just before the 5/10 split I was registering 58.1 and then lost it all through the slow traffic. I just can't get more than 43 mpg in town. I lose all of my extra mpg in town. I'm very happy with 45mpg.

Of course if you know these freeways, you know the cruise didn't stay at 65 through LA traffic.

 

Amen. Kinda crappy to have to deal with this diatribe thread of mfarmer1, when the overall vibe is remarkably positive on this site. Although, I still maintain his post is meant as a joke. That or being passive-aggressive with the Priuschat forum because of a bad decision....

 

mfarmer.....you said you were getting an aptera? i had never heard of it so i googled it. do you honestly think you are going to be able drive that thing safely at the speeds you were quoting? it looks like a "town car". i would be terrified to drive that out on a highway where folks are driving that fast. i doubt i would even drive it around town. im sure it would turn heads, but that doesnt impress me.

 

If you drive the way you say you do you won't get the EPA mileage rating in your Aptera either. My mileage in my Prius isn't as much as some here online but it's definitely 3 times better than my Tacoma and that suits me just fine.

I am a little concerned that it may take you more than a week to practice your driving. Seems to me if you really wanted to succeed you would give yourself a little longer to give yourself a chance.

 

This was a pretty personal dig too. There are people on here who are full-throttle environmentalists and some who believe the earth is flat- woops, I mean believe human beings have nothing to do with global warming.

The average American vehicle gets 20 mpg. Even if the average American vehicle only got your 38 mpg that would go along ways toward energy independence. Offshore drilling is fine, but why would we think Big Oil wants to drill for more. New refineries are fine if Big Oil would build some. But Chevron's CEO said they wouldn't as long as Congress was going to encourage solar and wind power. There is a new refinery on the way... being built by a Canadian company in South Dakota. More nuclear plants? Certainly, but we do need to be a bit careful. More coal plants? Well maybe if they were really "clean" but they aren't- coal gasification is promising but isn't here yet.

"Clean" is a bad word? Well, as you can see from where I live, I'm not worried about getting flooded in global warming. If it makes us more desert-like, I can adjust (I'm already starting to get old enough I like it warmer anyway!). I am worried about having to pay to keep Florida and the San Joaquin Valley from being flooded. Even George W. believes it's happening. He may believe or choose to believe it isn't our fault, but even if we're moving it forward by a few decades, that means a lot of money will have to be spent over the next few decades instead of over the next century.