New Prius only Averaging 38 MPGs...help

I'll give you a real-world example: My old Ford Aerostar van had a digital fuel meter that did a good job tracking average fuel economy. In perfect conditions that van would get 22 to 24 mpg. If you asked me what sort of mileage I got I would tell you "22, sometimes 24 mpg." In bad weather the mileage would drop to 17 mpg. That's a 29% drop, but only 7 mpg difference.

Once we bought our Prius and no longer took the van on the open road, the van's mileage dropped to 13 mpg - in the summer! Nothing was wrong with the van, only it suffered from short trip syndrome.

Tom

 

just did my 2nd highway trip and got 54 mpg (on the display). Didn't need any heat/air, all pretty level driving and averaged between 62 - 65 mph.

Does having your headlights on affect mpg? Didn't realize until this car that heat affects mpg (knew a/c did). The reason I ask about the lights, it is required to use headlights on part of the way and it seemed to lower the mpg, also thought maybe that's why they don't come with daytime running lights?

 

I think the headlights do affect the gas mileage slightly. They drain electricity from the battery therefore decreasing mileage. I always notice the battery drains faster when the headlights are on. This is why LED headlights should be standard or at least available on all models! Less drain!

 

We have over 18,000 miles on our Prius.

I even have Michelin Energy Tires, and Mobil One 0X20 oil with 4quarts in the crankcase so it is not over full.

All 4 tires have ( 195x65x15), 44 max PSI of Nitrogen with over 6,000 miles on them so they are well broken in.

Everything set up for the highest possible mpg, still not even near making the official EPA of 50 MPG in the winter.

Last tank was 43.58 calculated, in Oregon temps of 45-55 degrees.

My 2003 Jetta TDI (diesel) 5-speed manual / station wagon, is still averaging well over 50 MPG's this winter with nearly 130,000 miles on the odometer.

Just the facts

alfon

 

Same here with a Toyota Sienna. It is pretty scary the first time I saw mileage drop to 15, 16, or 17. Now I am used to it.

 

Yes. There is no free lunch. The headlights aren't a big hit, but it is measurable.

Tom

 

The headlights are negligible - 55 watts. Bear in mind that the engine is putting out 10,000-20,000 watts of energy to keep the car moving, so even if the headlights are 55W each, that's less than 1% of the total. With front AND rear defrost on, you'd probably notice it a lot more.

 

Hi - my prius 2010 has been driven for approximately 9750 miles so far - typically average about 53 mpg always always always for my normal commute ..... I would check what gas you are using. I made the mistake a few tanks ago to fill up with a blend that had ethanol equal or less than 10% added. Well my gas milage died ...... dropped into the mid-40's and the sad thing is it took a almost a full tank of non-ethanol gas to run through the vehicle before the milage improved - residual or maybe the computer ?

I'd check your tire pressure, verify the gas blend you are using (no ethanol), make sure the gas cap is fully on (one click thight), keep your vehicle in the eco mode (always) and watch your acceleration from the line - kiss the power zone verse keeping it floored until you reach 55 mph.

Let me know what you find out - Mr. Bill :rockon:

 

I think you got it dead on. A number of issues, especially salient to people coming from non-hybrid (or non-high mileage) cars:

1. - THe hybrids all give you instantaneous and trip mileage. Many older cars (and new ones) don't. If it isn't there, you don't notice it, ergo it doesn't exist.

2. - A drop of 5 (or 10) mgp looks huge. On a 50 mpg car, percentage-wise, it isn't, compared to a behemoth getting 20 mpg that drops to 15. (This is why much of the world uses liters/100km rather than mpg)

3. - Let's face it--a lot of us are 'anal' about our mileage. It's largely the reason many of us bought the car, so we have high standards.

as they say, ymmv.
Cheers
T

 

Drive it like you stole it, but it has no brakes.
Works for me!
4.3L/100km

 

new2hybrid,

I'm just curious as to what state or area you did your trip through that REQUIRED you to use your headlights in the daytime. You are lucky that in your 2010 Prius you have either halogens or LED's for your headlights. The LED's won't drain your battery as much as the halogens will, but at least you don't have to deal with the expensive failures that those of us who have the HID's are experiencing.

That's why I'm asking this question of you. Even though my Prius is a 2005 & hopefully won't have the same high failure rate as in the 2006 through 2009 (with the D4R capsules), I refuse to tempt fate by using my headlights in the daytime (unless encountering bad weather such as fog, rain, or snow). So I would like to avoid your area that requires the use of headlights in the daytime.

In your info block (to the left of your post) your location just says "Northeast USA", so I'm thinking that maybe on your trip you crossed the border into Canada (which does require daytime running lights), but if the daytime headlight use you mentioned is required somewhere here in one of the northeastern US states I'd like to know what area to avoid so as to NOT tempt getting a ticket.

There used to be a section of Route 44 in Massachusetts (starting at the rotary near the ramps to I-495 & going eastbound towards Plymouth) that only "suggested" the use of headlights at all times for safety because that road used to be 2 lanes of undivided highway that had more than its share of accidents [so I could see the recommendation to use your lights in the daytime there being useful to help save your life (but it wasn't mandatory)]. However, that road has been re-designed & is now 4 lanes of divided highway with guard rails too & I think they removed the "turn on your headlights for safety" signs.

Ken (in Bolton,Ct)

 

Not sure if it was mentioned but is it possible that something is mechanically or electrically wrong with the car? The dealer wont find it though. Was anything changed on the car, aftermarket radio, alarm, lojack etc..? 38 MPG seems low for 60s temps

 

IF you are driving around in SD such as the areas where our dotters live [Scripps Ranch or Rancho Bernardo], you will probably never get the rated mpg by Toyota. Why? Its too many ups and downs. When we visit either one of our dotters, we get great mileage going and coming home [to Huntington Beach]. While in those 2 areas, we get about what you are quoting. So, do not feel badly. Wait till you travel out of your area to get a better reading. In Htg Bch, we averate about 48.5 with our 2007 prius.

 

My scanguage with the amp x-guage (thanks to adrianblack's fine spreadsheet) revealed that the headlights draw 0.9 amps from the HV pack compared to no lights at all. The ready mode no-light draw was around 1.1 amps just for the ECUs and the current going to the 12V, jumping immediately and repeatedly to 2.0 amps when headlights turned on. Like an idiot, I failed to test the parking light only amps; perhaps someone else with a scanguage can look at that, since I do not have my SG in the Prius now.

For the record, I advocate headlights when required by law and in low-visibility situations. I do not recommend driving with parking lights. To each his own. Just reporting the HV amp flows I observed.

 

I got delivery a week back, and am averaging about 37 mpg (per the chart in the screen) for about 150 miles so far (mostly local roads with stop and go traffic) - 2 pips used in the gauge. I did not reset any mpg after i took delivery but the mpg is being calculated on ODO minus 3 miles (3 miles is what the ODO read when I took delivery). I have been driving in normal mode and normally as i would do with my older corolla. Reading all the posts here is kinda confusing - either i continue to drive the same way or try to adjust certain things??. End of the day, the car should break-in properly so that I hopefully get mileage atleast in the 40s after break-in.
- Someone said about using gas with no ethanol (or did i get something wrong)? Don't all gas have atleast 10%-15% ethanol content?

 

This is a really interesting thread. First time poster here. Recently got a 2010 Prius (Canadian model -- base with leather package). I am driving quite carefully, but I think the average I tend to get is around 7 L / 100 km. I think that's around 38 MPGs. The Canadian model has a simultaneous L / 100 km meter to the right of the speedometer. Is it normal, that when I drive at a slow speed, that the mileage should go up (if the enging is powering the car)? And, does anyone know what kind of an effect cold weather would have? Right now, in Ottawa, it is -15, with windchill should be hovering -25 or so. Unfortunately, we have to park the car outside...

Any advice would help!

 

Cold weather is bad, as is stop&go in higher-speed zones (hard accelleration to 35mph+, with fairly abrupt stops). Unfortunately this is "normal" conditions for some of us.

 

Well I live in San Diego also and mostly drive like I stole it and I'm averaging around 45 - 47 mpg. I do have a 62 mile commute and get the better mpg's when traffic comes to a stop and go. I have notice though that this cute little car is very sensitive to the fuel. I tried one station that the cost was .15 less then everyone around but my mpg's dropped to 40. Well I won't be using that station anymore. I should check my tire pressure I just relied on what the dealer put in. But I would suggest trying a different gas station. Gas prices and quality are erratic around here.

 

I've tried all different gas stations not noticing any changes to mpg, LoL. If there's a lot of hills and/or stop and go traffic where you accelerate more with gas than the battery, then yes your mpg will fall. I always have my prius in ECO mode, only if it's very busy and I have to get on the interstate do I put it in Power Mode. EV mode is about stupid because it limits your acceleration even if you stay under 25mph. you can drive around in parking lots with the battery only in ECO mode as well, just keep it below the line, lol. In rain doing 55mph, I didn't notice much of a hit to my mpg, maybe 1. The A/C doesn't take as much power as the defrost, so I use A/C on low during the summer, still get mid-50's mpg.

 

RE: Only averaging 38mpg?

Something has to be terribly wrong. Really.

For the past week I have been commuting ~ 30 miles each way to work, using the PWR mode exclusively. I've even found myself going 80mph when traffic permitted. Average daytime temps have been in the 30's. I accelerated up to (beyond) the posted speed limit with no thought to saving fuel...but I did coast when the opportunity arose. I was trying to drive this car pretty much like I drive all my other non-hybrid cars.

At week's end, my display said 48.2 mpg. I really have no idea how you can get 38mpg for any distances longer than a few miles.