Fighting to barely get above 35mpg

Welcome,
The 12v is suspect, not hard to test, be careful, there's no acc mode with the ignition like most cars, leaving the prius on with out being in "ready" will wear down the 12v in ten minutes, trickle charging periodically is good for mileage, using a weak 12v is bad for mileage.
2/3rd's-3/4th's up the dipstick for the oil, make sure your emergency brake isn't holding you back.
Drive the speed limit.

 

Welcome to Prius Chat! Thanks for filling out the "Questionnaire".

Read the attached file. The file is what the broken link was leading to. Lots of links got broken when the forum was redone a while back.

 

This question isn't suggesting to warm up. Unless its extremely cold, just try to take it easy on the gas for the first couple miles. I always get in, buckle up and get situated, then start the car and shift right into D and drive away (unless there's frost on the windows).

There's a lot of "I don't know" answers. The reason for the questionnaire is to give you places to look and possibly even find the solution yourself (such as finding your tires are all at 15PSI). It takes maybe 10-20 minutes (depending on how car savvy you are) to check everything the questionnaire has you check.

Your tires are pumped up, that's good. Check to see if they're LRR. 12v battery and alignment are two good possibilities.

 

Okay, a few things I will mention and then leave it in your ballpark.

I drove a Gen II for three years. It took me a year just to learn how to really drive it and then at least 6 more months before I became a pro at getting max MPG. So don't feel bad. Prius is not your average car by any means.

Based on the mileage of your car, I would recommend you change the spark plugs unless you know for certain that the plugs were changed before you bought the car. Make sure you use the correct plug when changing them. Also make sure the air filter is clean and that the throttle body and the MAF sensor is clean too. The plugs are supposed to be changed at 120,000 miles. Since you are dealing with a MPG problem, it would be a good idea to go ahead and change them.

With all that said, here are some comments based on your answers from the questionnaire.

Short trips like yours is not going to give you the greatest MPG in town, so keep that in mind.

Now, this could be good or bad. A lot of that depends on how much stop and go you are actually doing. Max speed of 45 is wonderful. 40 would be better if possible. In my signature below is a link on how to hyper mile a Prius. Study the link and practice what it says. It takes a while to get used to Pulse & Glide but after you are used to it, it will become second nature to you. When accelerating, don't drive like a Grandma, use a brisk acceleration without over revving the engine. (Don't floorboard it or make the engine roar...) Once you get to your target, then glide as instructed by holding light pressure on the gas pedal rather than coasting. When you coast or brake, the regenerative braking is slowing the car down and charging the big battery (traction battery).

You should definitely check the oil level. You want the oil just below the top dimple on the dipstick. You also do not want to let it get below the lower dimple. Check the oil frequently. I recommend every fuel up until you at least have an idea of oil usage if any. The capacity of the oil with a filter change is 3.9 quarts. Putting 4 quarts in with a filter change is "overfilling" the Prius and is a BAD practice. I recommend when you have the oil changed to change the filter and refill with 3.5 quarts. That will put the oil level a little below the top dimple. From the bottom dimple to the top dimple represents 1.6 quarts (not one quart like most cars). With that said, if you let the oil get down to the bottom dimple there really is not a lot of oil in the car. (3.9 Max - 1.6 = 2.3 quarts). Be certain to use 5W30 motor oil that meets the class L or higher and is also ILSAC rated. Synthetic oil is great if you are not using or burning oil. If it burns oil, try the "high mileage" oils. Make sure you confirm that the oil meets the minimum standard. Look in the owners manual for more info on the oil.

There is a link in my signature file below that will show you how to test the battery. Read the instructions on the linked page, run the test early in the morning BEFORE you drive the Prius, and then post back all three values you read. Gen II is a little different from Gen III as far as testing the battery is concerned.

If your car is not going down the road in a straight line or if your car is pulling to the left or right when going down a level straight road you should get a alignment. Also if you see abnormal wear, you should have the alignment checked and corrected. Your air pressure is where you want it, but abnormal wear could be a alignment problem or possibly worn struts and shocks. At the age and miles on the car, I suspect the suspension is getting rather worn.

My best response to your answer would be to look at all four tires. See if they match. Write down what you see concerning the model and size and update your post. FWIW, the tires play a rather big roll when it comes to the MPG on the Prius. It does best with LRR (Low Rolling Resistance) tires. Put a cheap set on, lose a good 6 to 8 or more in MPG...

Remember what I said earlier about hyper mile and Pulse & Glide. It sounds like you are not gliding correctly, but I am not there to see how you drive the Prius... The other stuff sounds great though about the red lights and the hills. When doing hills, as you approach a hill try to have your speed close to the posted limit. As you ascend the hill, allow the Prius to slowly slow down a little. Once you reach the top ease off the gas and let the speed pick back up. Try to glide as much as possible and only use regen when it is necessary. Remember when you regen the car is slowing down faster than when you are gliding.

Unless you are thin skinned like me and can not tough it out until the car warms up, DON'T let it warm up by letting it set. Once in ready mode, get it moving at least within a minute. Letting it warm up the way you are doing is wasting fuel and dragging down your MPG. The Prius will actually warm up faster if you start driving as soon as you are in "Ready" mode. Even faster still if you turn the climate control OFF. What you are doing right now is NOT what you need to do. Try it the other way like I mentioned above.

Also, there is a link in my signature below. It talks about S4 mode. Read the article and try to understand it. Pay attention to how the gas engine (ICE) shuts off in different ways as the Prius warms up. Try to get the Prius into S4 mode as quickly as you can. That too will increase your MPG.

When it comes winter time, do the grill blocking. Cold temps drag down the MPG too. Info on that can be found with a google search. Lots of tips on that here on Prius Chat.

Auto mode is ok however when you use the Auto mode, turn the A/C compressor OFF with the MFD when you are trying to heat the car. Even though the A/C compressor is driven by electricity, the electricity used still comes from the traction battery which is mainly kept charged by the gas engine (ICE) which has to burn fuel. The ICE uses more fuel which lowers your MPG when the A/C compressor is running. Regen will help to add a little electricity into the mix, but the bulk of the electricity being used comes from the traction battery whenever you are in "Ready" mode. Fan speed usage in auto is automatic. Some folks will even tell you to override that and control the fan manually. I did that at times, especially if I was riding with the windows down and compressor turned off. Depending on the temperature setting, the fan might run faster than the slowest speed which in turn uses more electricity. Climate control usage does factor in when trying to achieve the higher MPG. Use it sparingly when you can. In the summer when it is hot outside be certain to use the A/C. You want to keep the car cool. By doing that you also keep your traction battery cool. Heat is a enemy to the traction battery. Keep it as cool as possible. It seems most recommend 76 or 78 when using A/C. Me, when it is blistering HOT (over 100 degrees) I set mine on 74 as I want to be nice and cool during the heat of the day. Just remember when using the A/C the lower the temperature is set, the MORE electricity you will use.

Don't get stressed out, all that does is give you grey hairs. Remember what I said about how long it took me to really learn how to drive the Prius and refine the methods until I really mastered it. When I first started driving our 2009 Prius, I was getting about 42 MPG. Six months later I was getting 45. Six months after that about 48. Through adjustments in technique and changes with tires (Michelin Energy Saver A/S) and synthetic oil (Mobil 1) in the end when I traded it in on the new Prius I just bought my MPG average was running right at 53.

Finally remember the Prius is like other cars in this aspect. It gives it best MPG when it is warm outside. Blistering hot, the MPG will drop a little due to the A/C working real hard. Winter time is where the MPG will usually be the worst. Average on our Gen II during the winter was around 43 to 46, but during the summer could easily get 52 to 56, hence the 53 average. Also remember your MPG will vary. Also the MFD (thing on dash) and the numbers at the pump will not agree. That is due to the cursed bladder.

If you just drive the Prius like a regular car, you might get close to the EPA estimates. But if apply the tips, tricks, etc. and learn how to hyper mile, you should be able to easily beat the EPA estimates.

Best of luck to you,
Ron (dorunron)

 

welcome to priuschat! my guess is the battery. you should be getting in the 40's easily. i would check that first. all the best!

 

Let me just summarize some of the key points Megan.

Full economy aside, with a Prius at the number of miles you have it is vital that you check the oil fairly regularly. Prius of this age often have mild oil consumption, which doesn't seem to effect their performance in any way, but if left unchecked you can run low and turn mild into severe really quickly. If you don't know how to use the dipstick then it's time to learn, and quickly! Check it every 1000 miles, at least until you have established a trend of what type of consumption you have. Do NOT assume that there will be no consumption.

The best level for most people is near full (upper dimple on the dipstick) - but don't overfill. Measure on level ground after the car has been off for at least 10 minutes. Remove the dipstick and wipe it before re-inserting to take a reading. Err on the side of just under the full line rather than just over.

This could be significant. Poor wheel alignment will cause abnormal tire wear, and may also impair fuel economy.

NO! This question is one of the most important, as tire choice can make an instant 5+ MPG difference. This question is for everyone who can read, as the tire brand/type/size is printed on the sidewall of all tires.

It sounds like you're doing a lot of things right Megan. Just be careful not to try too hard with "letting off the gas" and running electric. It can be counterproductive if the SOC (state of charge of the main battery) drops too low, as the engine then has to work harder to try and recharge it.

One of the most significant things about learning to hypermile a Prius is actually learning when you should and when you shouldn't try to "EV" or "glide" it. Keep an eye on the 8 bar SOC display (on the energy monitoring screen) and try to avoid too many fluctuations, particularly below 4 or 5 bars.

This one is a little controversial. The conventional wisdom is that it's a waste of fuel to warm up, but my opinion is that a short warm up (30 to 60 seconds) is often beneficial. The HV battery often has a high demand placed on it in the first few minutes after a cold start, and you may notice a loss of one or more bars of SOC in the first two minutes or so of driving. If this is the case then a short warm up will generally improve the situation. Leave the car in "P" while it warms and you'll notice the green arrows showing that it's charging the battery, so the energy isn't really being wasted. No need to warm it for too long though, if you find that you're not "dropping bars" in the first few minutes then you're doing fine.

On final thing, sometimes the indicated MPG readout takes a little while to calibrate to your particular driving style. Especially if the 12V battery was disconnected recently (before you bought it for example), the reading can be off for a while. In my case it took about a month before my Prius started showing really good MPG numbers when I bought it secondhand.

 

If you follow everything that uart & RON have stated, your MPG will improve by at least 5, if not more

12v Battery, correct LRR tyres, correct tyre pressure and no warm up are the big things that I picked out - It does take time to get used to the Prius, I have mine 8 months and am still working on techniques. For me, I want to keep it over 50 mpg, (42 us ). I do mostly city driving, with red lights every few hundred metres, so 50+ is ok for me.

 

Hi and I add my welcome to Priuschat also.

While I agree with what Ron has said in principle, I have to disagree with him on the point of using the air on auto but with the A/C off. I would agree, except for the fact that just because the A/C is selected on does not mean that the compressor is running all the time it is selected on. The system only runs the compressor as required, and having the A/C on and in auto allows the system to use whatever means it needs to deliver what you are requesting of the system.

To me it also does not make sense to have features in a vehicle, that make your drive comfortable and enjoyable, and then not use them to save what I can see in my experience as an unmeasurable difference in fuel economy. In addition, the way the air defaults the A/C to on makes it a lot of phaffing around to switch off the A/C every time you switch on the air conn.

Having said that, if you don't need the air, just switch it off. Use it in full auto when you require it. If it hot outside definitely use it - if you're happy and cool, so will your traction battery. Close the windows when using the air.

Hope that makes sense.

 

Some red flags.

Check Your Oil.
Check your 12 vlt battery.
And if someone mentioned abnormal tire wear, check your alignment.

The MPG you are seeking, should be possible.
The questionnaire you answered might seem long but some of the " I don't know" answers you gave are in area's that can be crucial.

Best of luck.

 

I seem to do better with mileage by not using "auto" at all, as it uses higher fan speeds than I like and tries to heat or cool the cabin quickly, creating a lot of energy and heat demand.

I like to leave the climate control off most of the time and then use it in manual mode, usually at the first or second fan speed after a few minutes of driving. I wait until I'm done waiting at the second red light before turning it on. That way, the engine can stop while waiting at the light (it's a long one).

I've gotten some of my best MPG averages in heavy, slow-moving traffic. Slow traffic is a good application for the electric crawl (often not touching the pedals), with the engine off, keeping the speed as constant as possible (usually just a few MPH), "playing accordion" with the space in front of me. I noticed when I was riding with another Prius driver in heavy traffic, each time the traffic ahead began to move, they would apply substantial pedal, causing the gasoline engine to start (and spin at fairly high RPM) and then they would apply the brakes firmly when the traffic ahead stopped. This produces terrible MPG because of the high fuel consumption over the small number of miles traveled.

At higher speeds, you don't want to be completely off the pedal when you coast, otherwise some regenerative braking will be activated and slow the car down. For the best coasting, you want to apply just a little pedal pressure and maintain it, so that there's no regeneration. There's a sweet spot in the pedal where there's no regeneration and no propulsion (at 41 mph or below). This is the most efficient way to coast, or glide. It takes practice, but use quick glances at the energy flow screen to watch for when there are no yellow or green arrows. If green arrows show up, give the pedal a tiny bit more. If you get yellow arrows, back off a little bit. Above 41 mph, there will always be arrows, but you can still use that pedal sweet spot (by muscle memory) to coast.

Although the regenerative braking is more efficient than friction braking, it still has substantial losses (about 20% in charging the battery and another 20% when drawing from the battery), so minimizing flow to and from the battery results in better MPG (and longer battery life). The old adage to "avoid the brakes" also works well in the Prius. Maintain plenty of following distance and anticipate stops and slow-downs so you can use as little brake pedal as possible.

 

My '08 Prius also gets just barely better than my - 04 Corolla got - of course that was a manual xmission so it would just slow down on hills. I usually drive with traffic at 79.9 mph and get about 38 with no wind. On winter gas... Too bad they don't offer a manual xmission Prius!

 

Welcome to Prius Chat!

Please forgive me for how the following sounds. I know it sounds rash, rude, etc. I am not one to mince words or sugar coat things.

At 80 MPH? No wonder your MPG is in the tank.

Prius is not a race car. It gives its best MPG when driven reasonably. Anything over 65 and the MPG really starts to drop. 62 gives a good MPG. 55 is even better especially with NO A/C running. Best MPG out of the Prius - 45 MPH using the cruise control.

I know folks do drive the Prius fast like you are saying. They also report poor mileage as you are too.

Ron

 

You aren't paying attention. I know it's not "poor". I also know that if I slow down like you say the money I save is less than minimum wage - a lot less. It's a Touring so is a lot more comfortable than the Corolla!

I know folks do drive the Prius slow like you are saying. They also report good mileage as you are too. My time is just worth more than minimum wage, that's all...

 

Get up earlier in the morning! lol I live in a city where the max you can do is 80 km/hr (50mph), but the limit in most places here in Dublin is 50km/hr (30mph). Even our national speed limit is 120 km/hr (75mph)

If I was going to be driving at 80 mph, I'd have bought a VW of some sort with a 2.0TDI. Better mpg and comfort on motorways at that speed in a Passat or similiar than a Prius. My Prius doesn't like it when at 80+ mph

 

I don't think a VW TDI would get even 30 mpg at 80 mpg would it? Plus diesel fuel now costs more thanks to the low sulfur bs.

Other than revving high on steep hills the Prius Touring is very comfortable at 80. Well, compared to my Corolla anyway. Also, aren't TDI's hit or miss on dependability? Are they that much more comfortable at speed? I don't know - all that fukengruvin advertising stuff they used to do

Plus, if I got up earlier I could get to work earlier and make up more comp time - much more valuable than the money I would save! I check my mpg on a controlled 2 way flat run near my house at different speeds, then figure out how much I am saving per hour for the extra time at reduced speeds. Anal, I know, but with a 3 hour commute... With my Dodge Cummins diesel it's definitely worth it for me to slow down to 60 mph or so...

 

A 2.0 CR TDI 110bhp Passat (just an example) will do 40 mpg easily at 80mph on a motorway. My experience of VW TDIs I'd that they are quite reliable if maintained. It might be different with the ones produced your side of the Atlantic. A Passat or even a Jetta will feel a lot more solid on the road at 80mph than a Prius, I suppose mainly due to the weight.

3 hour commute! I'd be moving closer to my workplace of I was in that position.

Last week I had to do a 4 hr round trip commute for work. I did it two days in te Prius and on the third day I had a friends E280 CDI...that was a lot nicer for the commute. Mpg was reduced, but it ate the motorway miles.

 

One more possibility;
ask someone else who rides with you whether or not they think you drive like a crazy man ... its not your opinion that counts because we always think we fit in the average. I carpool with a fellow who every time he gets stressed ...I notice how fast he starts going on the freeway or how fast he's quickly approaching the next red light. Yet he bitches about barely getting 40 mpg. I try to help him understand but I don't come right out and say he drives like a maniac because he can't handle any kind of constructive critiquing. That's not meant to sound mean spirited ... it's just that some folks never realize how fast they're trying to get somewhere.
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