Newbie Questions - Prius Fuel Economy for Dummies?

[Tara1031]

Hi All,

I've been wandering around this site for the past couple of days trying to find an answer to my query, or possibly some help. You all seem very helpful and polite so I got over my shyness and figured perhaps the best bet was to just post, so hello!

I just got my new 2010 Prius II this past Saturday. I've been obsessed with this car for months and after tons of saving, it's mine. It's quite possibly the nicest thing I've ever had possession of; my last car was a '93 Infiniti G20. I love it. It's great!

My question, however, is with the mpg. I've read all of the manuals and have surfed the board and I'm still having a little difficulty understanding and using the different displays and gauges to see how many mpg I'm actually getting but I'm a little embarrassed to say I'm still confused. Does anyone know of/can point me in the direction of someplace on the web I can read up on this more specifically?

I drive about 17 miles to and 17 miles from work everyday. On the way in, I don't hit any traffic, so I hit up to 60 mph. On the way home, I usually sit in traffic and I use 'EV' mode when I'm crawling. The car came with a full tank of gas, and it's now Wednesday and I'm already half-empty. I've driven about 130 miles so far. Does that sound abnormal to anyone? It's probably just because I have no basis to compare this to, being my last car was not very fuel-efficient and I've never even really been IN a Prius before, so perhaps I have insanely high expectations?...

Just appreciate some thoughts. I'm aware it takes a little bit for it to "get settled" and it is fairly cold here (so that means I use the heat, etc...) Besides that, I would also appreciate some tips - I saw a few scattered here and there on the board but would like some all at once!

I really appreciate all the help you can give me. I know I probably sound ignorant and like a n00b but that's really what I am, haha! I am just so happy to finally have this car and to find a community of people that seem welcoming that I'm hoping for some help.

Finally - just a touch-up question - I noticed there's a scratch on the lower-door of the glove compartment today (probably from my sister getting in and out of my car with her bag) anyone have any advice in fixing this? I'm very retentive about that sort of thing and I'm so bugged it's there already!)

Thanks!

[PazPrius]

I wouldn't be surprised about low mpg's on the first few hundred miles, but if you get to the trip A or B indicator is does show the computer calucated mpg's which many find around 2 mpg's better than you actually get. Also I'm not convinced the dealer "Filled the Tank" as you or I would. Yes it says full but really did they top it off?

[spiderman]

, glad you joined us.

You will need to make sure after the first tank that it is filled up properly. I set the handle on the first notch, set it again after it automatically trips and remove when it trips the second time. Make sure to clear one of the trip meters at this time.

The scratches are a problem. The material is very soft and easy to mar. I don't believe anyone has found a full proof method to remove them.

Enjoy the ride!

[Tom183]

130miles is very low for a half-tank (even though a half-tank on the gauge is only 5 gallons). That's something like 26mpg, which is way low for a Prius, even in cold weather and adverse driving conditions.

So - possibly the tank wasn't full to start with, possibly it's still breaking in, possibly it's not really at a half-tank yet (possibly it has been more than 130 miles?)

First I would top it off yourself and reset one of the trip meters to establish a proper baseline.
Next I would check the tire pressures - need at least 35 psi front, 33psi rear. Just one tire well below proper inflation (especially one of the fronts) would have a major impact on mpg.
Last, I would wear a proper coat and not jack the heater too much - if you have a long stop&go drive and keep the heater >70F, the engine will have to run just to keep you warm. Moving nowhere (or very slowly) with the engine idling is pretty bad for mileage.

If you're not too married to the idea of keeping one tripmeter as your "lifetime" meter, you could use Trip A for the tank, and reset Trip B each leg of your commute so you can see what the mpg is in the morning vs on the return leg. This may provide a clue where you're losing the most.

Also check the grill blocking thread in the mods forum - I don't think it helps mpg much, but it seems to help with cabin heat which might be a bigger factor for your stop&go drives.

[omahajeff]

Hi fellow n00b! I also picked up my Prius this past saturday.

Good info from the other posts!

I have shown off my Prius to friends and while sitting parked with the car and heater on, my gas milege drops very quickly. If you are sitting in traffic with the heater on you may see your mpg go quite low. It's cold here as well and I keep the blower set low and the temp set at about 69 or 70 after running it full blast for a couple minutes to initially warm up. I like it cold though!

The best way I found to get used to all the displays is to just drive around a big empty parking lot. I did that for a while and got used to the sheer amount of information you can get. Made it much easier to absorb that information on the road. Almost like learning on the job!

I've settled into using my Trip A for daily MGP reports driving to and from work. I reset it each morning. I will use Trip B for each tank.

Good luck!

[johalareewi]

Originally Posted by Tom183

...
If you're not too married to the idea of keeping one tripmeter as your "lifetime" meter, you could use Trip A for the tank, and reset Trip B each leg of your commute so you can see what the mpg is in the morning vs on the return leg.
...

If you want to keep a lifetime MPG you could use one of the web based fuel logging sites like fuelly.com

I use one trip meter for the tank and the other for the trip and fuelly.com for the cumulative history.

[Tom183]

Yep, and a spreadsheet works too - you just have to be sure not to create any gaps in the data.

To get the worst possible mileage in the Prius, start the car but stay in Park, reset the tripmeter, then turn on the heater full-blast along with both front and rear defrost. Headlights and wipers will add a tiny bit also.

Sit there for about 5 minutes or until the defrosters shut off, then drive 1/10th of a mile to give the meter some distance to factor in (it will read 0 until it has some distance to calculate with).

I haven't done this, but would expect it to be some decimal under 1mpg.

Which leads to this observation: it's best to start with the heat off (or in "auto" with a temp of 68F or less) and get moving before cranking things up. The mileage penalty will always be worse when the distance is smaller (given the way division/multiplication works).

Also: try ECO mode for your stop&go leg, it tends to be more aggressive about engine shutdown when stopped, so there should be less idling (and better mileage).

[jomiku]

I would bet the tank wasn't full. I have only had my Prius for a week and I wondered what the mileage would be but I waited until the first bar plus had dropped off the fuel gauge - no reason, just wasn't thinking clearly. The mileage was low. I then reset the odometer and waited until the first bar sometimes dropped off. That showed 45 mpg, which given the many short drives I need to make and how cold it is and that I haven't checked the tire inflation, is fine. The tank was clearly not full when I got it.

[JimN]

Tara, welcome. The MID (IMO Mis-Information Display) takes some getting used to. The car's calculations are optimistic but can be used as a rough guide. I'd run the first tank down to 1 or 2 pips then fill up. I keep track of lifetime FE on a spreadsheet & use trip A for the tank.

Blocking the grill retains heat so the ICE doesn't run as much. Inflating the tires to max. sidewall pressure increases tire life, decreases rolling resistance, and increases traction on wet pavement. I keep the heat off for the 1st 5 minutes as the car needs it more than I do. Climate Control is manual at 74F with fan speed at 2 bars.

Crawling or parked in traffic kills FE especially if you need to run the heat. Experiment between ECO & normal modes.

Plugging in a ScanGauge will provide more information to enable you to improve performance.

Unless you tried topping off the tank you don't know how full the car was. As long as the tanks keep improving things are OK.

[Tom183]

I tried higher tire pressures today - went from 37/35 to 41.5/39.5 (wasn't shooting for .5, it just worked out that way). These are my snow tires, so they're soft to begin with, but they're rated for 44psi (cold), so I felt pretty safe with those levels.

Big difference, as far as I can tell so far - it may be a bit more than 3mpg, and it seems to apply equally to "around town" and highway speeds.

My gauge this morning (with the tires at the lower pressure) was staying right around 45mpg displayed (42.4mpg actual when I filled up on the way home), this was from "around town driving" and some playing around with P&G, albeit in somewhat colder temps (low 20's F). 47mpg displayed is a little more normal for temps near freezing like today.

I was at home long enough for the tires to cool all the way down (the engine didn't get all the way cold but fairly close), so I pumped them up to 41.5/39.5 and went for a little test-drive later in the day. Display easily went to 50mpg and stayed right around there for "around town" driving, so I made one brief stop at a store then hit the highway for about 18 miles mostly at 70mph. I used Trip A for the highway test, it settled in around 46.7mpg displayed by the end - I have seen as low as 41mpg displayed for highway on an especially cold trip (high teens F).

So my guesstimate is about 3mpg difference with not quite 5psi more in the tires - won't know for sure until I have more miles in colder temps, but it's definitely at least 2mpg (4-5%).