Really bad gas mileage on 07

<div class='quotetop'>QUOTE(Prius happy @ Nov 30 2006, 12:50 PM) [snapback]355757[/snapback]</div>

I have exactly the same experience with my '07. A strange thing is that one day I was getting 54 mpg, the next day 32 mpg. I was told the same thing as you when I complained to the dealer. I never got 54 mpg again. Something is screwy and I don't know what.

 

Letting your car warm up always lowers your mpg. I never let my car warm up more than 10-15 seconds, And I don't sit and let the Prius warm up. As soon as I see the ready light I am into reverse and backing out of our carport. I think the main thing is to just go easy on the gas pedal for the first mile or so while the engine is warming up. I also don't go over 70mph on the freeway. I don't need to, I'm not in a hurry and I would rather let the speeders go in front of me so they will get ticketed and not me

So far I have 550 miles on the car and the MFD says this current tank is getting me 42.8mpg which isn't all that bad considering it's been in the upper 30s around here lately.

Driving to Portland this weekend, first real road trip, and will see how she does!

Dave

 

<div class='quotetop'>QUOTE(Prius happy @ Nov 30 2006, 09:50 AM) [snapback]355757[/snapback]</div>

So, do you REALLY think your 95 Subaru would get above 30.6 in the exact same conditions w/the same habits (warming up the car and everything)? It seems unlikely.

Just for reference, when Consumer Reports tested the Prius, they got 35 city/50 highway/44 overall. See http://www.consumerreports.org/cro/cars/bu...s-206/index.htm and http://autos.msn.com/advice/CRArt.aspx?contentid=4023460.

Most of the suggestions here I've seen are good. Definitely do NOT warm up the car. Also, having the heat on (unfortunately) can force the ICE to run more than it should. I've witnessed this where I'm stopped and can hear ICE running and right when I pressed OFF on the HVAC system, the ICE stopped.

If you use defrost (and possibly the auto setting), the (electrically driven) AC compressor will run part of the time, further hurting your mileage.

My first "tank" was a not so good 38.1 mpg (45.1 mpg on the MFD). There have been lots of possible explanations as to why the first "tank" is bad for people in another thread (dealer driving it around short distances for prep, dealer not filling up all the way, etc.). My lifetime avg. is ~45.7 mpg now.

 

(Nobody has mentioned tires yet?) Cold weather makes tires go soft, which also reduces MPGs. Check tire pressures at least monthly and whenever the average outside temp changes more than 10 or 20 degrees. Many of us fanatics keep our tires at 42/40 PSI front/rear for better fuel economy. (But note that this also changes the ride and handling noticeably.)

If you're lighting up the slip indicator then you're driving with a lead foot. Easing up will improve MPGs.

 

My first tank this summer was just over 30 mpg....from then on, I have been 42 mpg...I do the worse kind of driving...short trips, but I follow the suggestions here and I believe they have helped.

Now, the weather turned suddenly cold...20s...this tank is at 36 mpg right now, but I have a couple of longer drives coming up and it is early in the tank. I totally agree about warm-up. If it is cold and you let the car sit after turning on, the mpg can drop quickly just sitting there.

I drive it while it warms up.

terri

I expect my mileage will drop in winter...grggghhh...glad I got it in summer and got above 40 mpg after that first scarey tank.

 

During the first 5 minutes of my daily 45 minute commute I get 25mpg based on the bars. For the rest of the trip the bars indicate very high 40's--very low 50's.

Check your tire pressure as it is probably low from the dealer.

The fuel gauge (aka the "guess gauge") is almost useless and the computer's calculation is a shade optimistic. I calculate when I need to buy gas based on the MFD's displayed distance and economy. Start looking for gas when you get down to 1 pip. When it gets "low" a beep will sound and the pip will flash. Don't panic, there's still plenty of gas in the tank. Don't fill past the automatic shutoff.

I think the early oil change is BS. I change oil and rotate tires every 5000 miles (done once so far) to stay within warranty. When the warranty expires I'm going to extend the oil change interval because at 2500+ miles the oil looks new.

You can track your mileage at www.greenhybrid.com where there are 7 active posters with less than 40mpg.

I think we have all improved our driving habits because of the data provided by the display.

I took delivery at the end of July and it has just started getting cold here so I'm going into my first winter experience. Thanks for the heads up.

 

Last week during the cold snap here I let the car warm up (left it running), and the MPG plummeted. Now when the weather's cold I hang a hair drier from the rear vision mirror with a timer. (It's a trick I learned 10 years ago when I had an EV with no heat whatsoever).

 

<div class='quotetop'>QUOTE(richard schumacher @ Dec 8 2006, 10:28 AM) [snapback]359308[/snapback]</div>

I don't think you've driven traction-control vehicle in snow/ice. If it's icy, even a little acceleration will cause the tires to slip, and it doesn't have to be both drive tires either. There's a stop sign on the way to work with some good snow that was packed to ice last week. The first time I stopped there, I tried to accelerate as normal (I do NOT have a lead foot, my wife will attest to that), and the tire was slipping for several feet as I slowly got up to about 5 mph. Then I hit some dry pavement and it suddenly accelerated like normal. I was really surprised how powerless it suddenly becomes with one tire on ice. My last 6 years were with the Subaru Outback (AWD), so apparently I need to relearn some of my northern-Minnesota driving skills.

I like the hair drier idea. That would be a good way to warm up the interior before leaving the house more efficiently than using a large ICE.

I got up to 55 mpg last summer (lifetime average was 49.93 before the cold weather hit). This tank was struggling to be around 40 on the MFD, but now with the warmup it's improving. That was with temperatures in the 20's and 30's F (0'C to -8'C) during driving hours.

 

<div class='quotetop'>QUOTE(nerfer @ Dec 12 2006, 03:19 PM) [snapback]361028[/snapback]</div>

Ahem. Well, hectually, I do, although not every day, and I stand by my advice: if the original poster gets the anti-slip they should try easing up.

 

Me too! First couple months were great - up to 49 mpg average. Now 43 at best - usually 34-36?? Also, the "ready" light stays on constantly - is there any correlation here?

 

This spring with 20 mile commute and 40-60 degrees I was getting 56 mpg. On this tank temperature has been up to 102 and I have been making lots of short trips in the hot afternoon instead of regular am/pm commute.... 42 mpg. Makes a BIG difference depending on the type of trip you make and how hard your Air Conditioning is working, I keep mine on 80. Short trips when hot = lots less mpg. Probably short trips when cold = lots less mpg too! But I think the AC has a lot to do with it. Also, Ready Light means just that, the car is ready to drive. Its always on if you are in driving mode.

 

<div class='quotetop'>QUOTE(Marlin @ Jul 6 2007, 03:17 PM) [snapback]474209[/snapback]</div>

Thanks - yes - it is hot as the hinges of hell here so I will check the AC setting for sure before I scream at the dealer more. Thanks for the reply.

 

Check tire pressures also at least monthly. Many of us use 42/40 PSI front/rear to improve fuel economy, at the cost of a harsher ride.

Keep in mind that the battery system gets its cooling air from the cabin. If the battery system gets hot its efficiency, and thus your fuel economy, will drop. Rule of thumb: if you are uncomfortably warm then so is the battery, and you should turn ON your A/C. (Yes, this is one more way in which Prius is not like conventional cars.) I keep the A/C running all the time in Dallas and get 45 MPG even so.

If you do not have covered parking during the day consider a custom Sunshade for the front window, and then park facing south or southwest. Many Toyota dealers have these; I'd recommend the folding style and not the roll-up.

 

<div class='quotetop'>QUOTE(daniel @ Dec 1 2006, 09:53 PM) [snapback]356508[/snapback]</div>

A terranium/reptile fish tank heater that looks like a pad that is between 15 watts and 50 watts might help if placed under the batteries. Just a suggestion. I need to try this myself but I live in GA so I don't think it will help much. If you could get ahold of some heat trace wire that dosen't get too hot that might work too for winter only. IMHO.....This is in theory only for now.

D Rock

 

To sum it up:

Your mileage sucks because of the following factors:
1) It's too damn cold
1a) You probably have your grill unblocked. Block it to reduce heat loss from the engine block. See "Grill Blocking".
1b) The prius coolant never reaches 70c, where it begins stage 4 operation mode. See section 1i: EBH
1c) Your using the cabin heater, which causes the engine to stay on to produce the heat that you want.
1d) Your model may not have the thermos, please give us your location so we can tell for sure.
1e) Low temperatures also lowers tire PSI, pump them up to 42psi front /40 psi back ASAP.
1f) Cold air is more dense, requiring more energy to push through it.
1g) Cold air requires more gas in order to maintain proper fuel/air ratios.
1h) Battery is not in operational temperatures. Consider parking in a garage.
1i) You don't have an EBH installed. Consider using on to "warm up" the engine to 55c temperatures, giving you the added boost that can increase you chances of reaching stage 4. See 1b & 1c.
1j) Transmission oil doesn't have much of a chance to warm up. Efficiency improves as it heats up. Nothing you can do about this.
2) Short trips
2a) Short trips reduces the chances of 1b occurring.
2b) The engine isn't warmed up, thus it isn't as efficient, see 1g and 1b.
3) New Car
3a) You haven't quite mastered the art of driving the prius yet.
3b) The engine isn't broken in yet. Engine efficiency will improve as parts are worn in.
3c) Tires aren't broken in. Tire mileage will improve as they're broken in.
3d) Low tire pressures. You'd be surprised as to how low those tires are when they arrive at the dealer. See 1e.
4) Inclement weather.
4a) Snow/ice requires more energy to push through.
4b) Tire slippage wastes energy by definition.
4c) Snow tires reduce mileage due to their design and aggressive treads.
4d) Headlights on causes more energy to be used.

Also, I'd recommend using synthetic oil in those temps...

 

I was also told by the dealer that oxygenated gas is crappier for mileage in the winter than regular (non-oxygenated) gas that is typically used in the summer.

 

E10 gas used regularly causes a 3% MPG reduction. You may see a greater reduction on the first tank or two if you had water in the fuel tank or crud in the injectors. Cold weather has a much larger continuous effect.

 

Don't worry about MOST posters ~ just look at their avatar to see where there winter is. We've done winter in Montana (btw, your avatar doesn't say where you live / drive ... that would be helpful). We've done zero degree drives through a whole tank, and after practive, never got below 50mpg. That's with the grill 100% blocked (which I even do in So Cal winters) and with a stock Electric Block Heater that you can buy here at the Prius chat store. Have it installed, use it (it'll make your car heater work great too), block the grill, and switch to 0w-30 oil too. You'll instantly get an easy 20% better mpg. Don't forget, you car isn't broken in yet. It will continue to get better over the 1st 10,000 miles. Hang it there, and BE PATIENT . . . NOW!