We bought our 2004 Prius a year ago, and while we never expected to get EPA milage figures, I did hope to get 45-50 MPG. In fact, with ordinary driving, we get only 36 MPG city, 44 highway, which is not only low, but the opposite of what Toyota says we should get (supposedly higher in city driving, a bit lower highway). Also, it seems strange that in low speed city driving, the gas engine kicks in at very low speeds (5+ mph) even when the driving battery has a good charge in it. Any other observations like ours ?

 

That is quite a bit different than my experience.

Where do you live ? I often think the best thing to do when these outlier mpg's are reported is to hook up with another Prius driver, and switch cars for a 20 mile trip, and see what kind of results are reached. That way you can sort out the car from the driver ..

Perhaps there is a Prius enthusiast club you could hook up with ?

Good Luck -- Eric (in Abq, NM)

 

Could you give us some more information?

How long are most of your trips - short trips decrease mileage substantially.
Do you use AC?
What tire pressure do you have?
What type of load for your typical driving - 1 or more occupants, cargo?
What are your highway speeds?

Your mileage values do seem very low.

 

As EricGo eluded, the driver is one of the primary components in determining how well the Prius performs in FE. For example, I consistently get tanks in the mid to low 50s without trying at all. I'm not out to prove anything anymore with the Prius so I "just drive it". My wife, however, has repeatedly asked me what technique I use to get above 50MPG and she is never able to do it. Setting the driver issues aside, lets look for a few other culprits.

Tire pressure: I run 42/40 front/rear and enjoy consistent mileage. I have even set a maintenance reminder that reminds me to check the tire pressure every 1500 miles or 30 days. Without fail, I'm always down a pound or so. Make sure you air up with cold tires. If you don't have a compressor at home make sure you stop at the station that is closest to your house.

Air Filter: As with any ICE, if it can't get enough air, your fuel economy is going to be heading south. Pull it out and look at it carefully. If there is any hint that it may be clogged up just toss it and get a new one. I'm waiting for K&N to come out with a filter for the Prius, but none yet. Help us all by letting K&N know you want a filter for your Prius by visiting http://www.knfilterchargers.com/products_needed/

Oil: Check your oil on a level surface after sitting for at least 1 hour after running it. Make sure the engine is not over or under filled this can impact FE and will damage the ICE in extreme cases. Make sure you are running the best weight of oil for the temperatures and driving conditions you are currently in. (Many others on GreenHybrid have done research on what oil weights work well.)

Alignment: The alignment of your vehicle can have great impacts on the FE. Long before you see abnormal tire wear patterns you are creating additional resistance against the road surface. As a rule, I'll have my alignment checked at least once a year on all of my vehicles and about 50% of the time they are out of spec. Colorado DOT takes great pride in the size and depth of their potholes on I-70 and I-25.

Fuel: Check your fuel. I can see 10 - 15% FE differences if I use "bad" gas. I would rather pay 3-5 cents extra a gallon to buy from BP, Conoco, etc than save $.40 on a fill-up. Often the BP and the Mom-n-Pop shop across the street will buy and receive their fuel from the same gasoline wholesaler and all of the gasoline comes from the same regional refinery, but conditions of the storage tanks and filtering equipment can make a difference. At the very least give the fuel at a different station a try for 3 tanks and see if your FE improves. Make sure you are meeting the minimum octane requirement of 87. At high altitude you can probably run 85, but if your octane is too low you'll get pinging/knocking and that can kill your engine, not to mention your FE. Don't buy into the Premium or Super being able to clean your engine or thinking that the octane rating will get you better FE. Octane has to do about operating correctly with your engine as the viscosity (weight) of oil does, it doesn't rate the bang (or BTUs) you get out of your fuel.

Ok, now I'm going to go out on a limb a bit. I'm sure that some will disagree on the importance here: Fill up fuel consistently. Don't bounce between different grades and/or different brands of fuel. The computer in your car has to adjust to the differences in fuel for every tank. During this adjustment period you certainly are not operating as efficiently as you could be.

Mechanical: If you get through the rest of these steps and don't find anything wrong, consider taking it into the dealer. Explain that you are dissatisfied with the FE that you are receiving and let them know the steps you have gone through to improve the FE. Ask to have your vehicle checked for other issues such as a dragging brake shoe, abnormal engine operation, etc. They may require a basic diagnostic fee if nothing is found, but it should be nominal.

Lastly, let us all know how it turns out. What you try and what, if anything, seems to help the situation.

 

PrimeRisk,

Brilliant post.

I am a bit confused though, as to which driver I was eluding
Unless you are alluding to my wife, who is an MPG kamikazee

 

I bought my 2005 Prius not because of gas mileage but because of the technology in the car. The mileage was an added bonus. I'm averaging about 37mpg with my Prius, and at first I was a little put out, but then I thought about what was involved in my daily driving experience and it started to make a little more sense.

I live in Minot, ND. Minot is a small city situated in a valley. Driving across town takes all of five minutes, seven if it's rush hour. To get anywhere, you have to go uphill. My commute to work takes three minutes if I get all red lights. These factors play heavily in my mileage. First, most folks say that you need to drive the Prius for at least five minutes before the car can be efficient. I'm sure I'm wording that wrong, but the point is that a three minute drive to work isn't going realize the mileage that a seven minute drive will. That might even be in the owner's manual, I don't remember off hand. Second, driving uphill requires more horse power than driving on a flat road. That's going to eat into the mileage. Third, rapid start and stop driving never gives the Prius a chance to conserve energy. In Minot, if you can go for four blocks without stopping for one reason or another, you're doing pretty good. We have stop signs and stop lights everywhere. Additionally, a lot of folks around here see traffic control as more of a suggestion, than a rule. A day doesn't go by that I don't have to slam on the breaks for some idiot running a red light.

37mpg didn't seem all that impressive, but when I talk about my mileage with my friends who have conventional "efficient" cars, they usually get upset. They are all trying to break 30mpg when I'm trying to break 40mpg. I may not be getting all that close to the numbers on the sticker, but I'm still getting pretty good mileage for the area.

As a disclaimer, I've noticed about three other Prius' (Prii?) in town but I haven't had a chance to talk to any of those drivers. I'm hoping someday soon I can compare notes with them. I may be getting better or worse mileage than them, I don't know.

 

You super short commute folks would do great with pure electric cars if/when you can get one. Range is there biggest negitive and with such a short commute range is not an issue.

 

The EV button mod could also improve the situation, especially if your drive isn't high speed right away. Most people find that the ICE doesn't really need to be fired up right away, and is better off providing some power while it warms up the catalytic converter, or at least rolling along. Hard to say if such a short trip would actually benefit it that much, but a slightly larger battery pack and you'll be able to drive the whole way on EV alone! All you'll need is a home charger and you'll be using a virtual EV.

 

Yes, I agree. For short trips (`3 miles) under 35 MPH, EV is fairly easy to do. I have the batteries and charger to do just that. But since I have a 25 mile trip to work, I have found that it is just easier to leave the batteries at home and let the Prius do it's thing. With trips that long, the benefit of grid charging for me is not worth the effort.

 

I have a 2005 Prius (since March) and get 52-60 MPG Highway and around 30-32 MPG city. Averaging 50-52 MPG.
If you have a lot of stop and go driving you will be lucky to get above 30 MPG in the city.
There is a technique to getting the high MPG's.
This seems to work for me. . .
When pulling away from a stop, traffic allowing, press gently on the accelerator, letting battery power get you to 7-10 MPH then get press harder to 'QUICKLY' get up to speed.
Then take your foot completly off the accelerator and press it back down, this should be in less than 2 seconds total.
If you are 40 MPH or less the battery should then kick in.
If you apply constant pressure to the accelerator, the battery seldom kicks in.
It needs that momentary pause.
On the highway try to keep the accelerator at a constant position.
If you are going up a slight hill, let up on the accelerator (to drop speed 1-2 MPH), then as you level off accelerate to 1-2 MPH above limit and then back off to speed limit.
For the battery to kick in (most times) you have to go a little faster than your desired speed then let up on the accelerator just a little.