The novelty is wearing off...

Regarding fuel mileage, I recently learned a lesson. I change my own oil and use Castrol in everything. I accidentally put a quart of 20/50W in with the 5/30W I usually use in the GenII. I was surprised to see that this cut my MPG by 5 or more. So, I conclude that these cars are basically walking a tight rope and any little item can throw them off balance, especially oil and tires/tire pressures. Driving habits too, of course.

If nothing has changed appreciably regarding tires and so forth, then I would suspect critical items such as 02 sensors, air flow sensors, etc. Testing can quickly and fairly economically confirm the status of these items.

If it isn't getting 50MPG dependably, then I would go looking for the problem.

 

Why does everyone keep talking about "low-50's" as the benchmark for the Prius? I am three weeks into owning a pre-certified 2009, and the best tankfull has been 44 mpg, which coming from a 12mpg GMC Suburban is astronomical. In fact, I believe the 2009 was only rated 48/45 by the EPA (and we all know how over-rated and bogus their mileage estimates are). So how in the world are you guys getting low-mid 50's?

 

We drive the speed limit?

Seriously. If you drive on the freeway/highway at 65mph there is no reason you shouldn't get 50+mpg unless you have one or more of the following issues:

• Heavy AC usage
• Non-LRR tires
• Under-inflated tires
• Bad alignment
• Very cold or very hot temperatures
• A number of short trips on your current tank
• A failing 12v battery
• A failing HV battery
• 17" or larger wheels

Any one of these could push you below 50mpg on a highway trip. Weather must always be taken into account as well. If you have only owned the car three weeks then you may be working against colder than optimum temps (60F-75F), winter fuel blends, and inexperience with driving a Prius.


To rule out short trips or a bad commute hurting your mpg. Try taking a highway trip of at least 40 miles. Reset your mpg gauge and maintain a speed of 60-65mph. If you don't get 50mpg or close to it then you may have one of the above listed problems.

 

Your realized mpg will depend upon the commuting that you do (whether longer or shorter trips), the terrain that you drive over, the fuel used, and the condition of your vehicle.

For example when I lived in south Orange County (CA) my realized mpg was in the low 40s. I attribute this to terrain (driving from 1,200 ft elevation to sea level) and the lower energy content of CA gasoline. Now that I live in southern AZ, my fuel economy is in the low-50s without effort. Freeway speed limit is 75 mph here, and I keep up with prevailing traffic.

 

there could be other factors as well. Dirty MAF sensor comes to mind, but the point is there could be a mechanical problem. Most of the time it is just learning to drive the thing optimally, and choosing to do so.

 

I know plenty of people who get 38 MPG. They just don't come to forums to brag about it

 

dstrauss said

What most of us know seems to be different than what you know.

Between the driver, trip length, and road/traffic conditions a wide range of MPGs are reported. I suggest you figure out *why* your fuel economy is on the low side; then you will know if you have a choice in improving it, or even want to.

 

I'm with you dstrauss. Despite my best efforts, (tire pressure @ 44/42, pulse and glide, hypermiling etc) I still only get about 44 or less on my '06 and about 40 on my '01. The first 5 minutes is a killer (usually 25-30 mpgs) the next five minutes varies from 50-75+ but it doesn't make up for the first five. If I average 25 the first 5 and 50 the second 5, (assuming I traveled the same distance in both 5 minutes), its 37.5 mpg. I attribute my low (relatively) mpg to the short trips I do. I rarely drive the car longer than 15 minutes (most of the time 10 min or less). It seems this is the achilles heel of the Prius just to satisfy the EPA and CARB (it seems well intentioned regs caused another limitation to progress).

The bottom line, I'm still getting 44 mpgs in the city. No other car comes close for the price, not the Civic Hybrid, not the Insight, not the Volt. I paid $10k for the car (used) and couldn't be happier.

 

It's not a limitation to progress. The car is designed for low emissions so the warm up cycle is critical to keep emissions as low as possible.

 

I was on a highway once. Damn, it felt nice to finally see the meter go north of 50 MPG.

 

imho, its a limitation to progress. Burning more fuel to keep emissions low, makes no sense to me but, I really don't want to get off track of this thread.

 

It seems like the two big impediments to really high MPG are 1. High speeds and 2. Short trips. It's 80+ MPH speeds in dstruss's case and short trips in your case.

I usually get around 40MPG for the first 5 minutes and mid 50's after that. Most of my trips however are about 20 minutes or more, so I usually average around 53MPG.

Warm up is an interesting problem. I often let the car warm up just sitting in "P" for about 40 seconds and strangely it actually seems to slightly help my fuel economy rather than hurt it. It charges the battery for that 40 seconds, so the "warm up fuel" isn't completely wasted.

 

To All Who Replied to My "Low-50's" Comment

1. [uart] The legal freeway speed limit in most of Texas is 75, with many 80 portions. I've never gotten over 70 whether my Prius or former (now dead) suburban, not even downhill (can a Prius even go 80?).

2. There is no way to safely drive 60-65; so if that's what it takes, I have to say I love my 44mpg highway refill (at 70)

3. [Sagebrush] The EPA did give the 2009 Prius a 48/45 rating, and I stick by my assertion that the EPA ratings ALWAYS overstate actual highway mileage figures:
http://www.fueleconomy.gov/feg/noframes/25987.shtml

4. [F8L] Maybe tire pessure/temp are effecting things, but I just bought it off the dealer lot as a pre-owned certified (warranted) vehicle, so it just passed the Toyota 160 point test for the extended warranty coverage.

I agree 110% with usnavystgc: "The bottom line, I'm still getting 44 mpgs in the city. No other car comes close for the price, not the Civic Hybrid, not the Insight, not the Volt. I paid $10k for the car (used) and couldn't be happier." Except mine cost $14k.

Thanks all!

 

Ok I kind of assumed the 80 thing based on the other thread where you said most people in Tx like to travel about 10 MPH over the limit. Anyway mid 40's MPG at 70 MPH is ok, there's nothing wrong with your Prius. Typically it would increase from the mid 40's to low 50's as you slowed toward 60 MPH.

BTW. I'm pretty sure the Prius can manage 80 MPH. There was member here that once posted a picture of their speedo while doing 108 MPH on one of the Autobahns in Europe.

 

My wife drives our 2008 like a normal car. Put it on the floor leaving a stoplight, etc .. we average about 40 plus or minus 1 or 2 in mixed driving. We have taken a trip across florida where speed limits for were around 50mph and our mileage was in the mid fifty's 4 the trip. When we drive north of florida or mileage goes up significantly, I do not know why. 75 miles an hour we were averaging 46 miles per gallon through georgia. So in short, the mileage varies greatly depending on your driving conditions and driving style. But in daily mixed driving about 40 miles per gallon has been our average. Also the mileage did go up as we got more miles on the car.

 

It's not that the EPA is wrong. It is people who break the law who cannot get the EPA rated mpg. I travel at the speed limit (65-70mph) for my area and have no problem beating the EPA. With 98% freeway miles as part of my commute I am at least 5mpg over the EPA.

Have you told use what kind of tires you run? I cannot remember if you did. Either way, you're doing well considering your speed. All vehicles lose mpg as speed goes up. I tracked my GF's daughter's 2001 Civic with my scangauge at 60mph it was sitting in the low 40s but as soon as I took the speed up to 80mph the mpg dropped into the low 30s. Too bad all the giant truck and SUVs owners don't have a scangauge so they can see how much fuel they waste while they speed along pretending to be patriotic.

 

Slightly rearranged:

Of course it can. Don't you remember Al Gore's son getting busted for DUI at 100 mph in a Prius? Its speed limiter is slightly higher.

Just keep in mind that #3 is strongly linked to #1 & #2.

In my state, only three roads have any portions with 70 mph speed limits, none are higher. Most of my driving is on slower roads. Nowhere have I found any portions where 60 is too slow to be safe. Even where average speeds are higher, 60 is still within the normal and safe speed distribution. I haven't driven 70 since the Hurricane Katrina gas price surge.

In all my household's cars in these driving conditions, from 1986 onwards, the EPA rating has understated the actual highway mileage figures. Though the 1997 car (still in the household) took a few years to get the nut behind the steering wheel properly adjusted to achieve these results. All the others beat their EPA highway ratings from the first tank.

 

I've gotten a tank in the very low 50s in the past when I kept my speed below 70 mph for an entire tank.

http://priuschat.com/forums/other-c...uth-about-epa-city-highway-mpg-estimates.html should prove insightful. Besides the EPA procedure calls for not driving on a real road nor measuring actual fuel usage, the highest average speed on any test cycle is only 48.4 mph. If you look at the test schedule, even on the high speed test, the car spends most of its time under 70 mph.

http://web.archive.org/web/20090201...-advice/most-fuelefficient-cars-206/index.htm were CR's test results. The last page of http://www.consumersunion.org/Oct_CR_Fuel_Economy.pdf describes their tests vs. the old EPA tests.

 

Dstrauss, "actual" results do not differ from EPA, unless "actual" are different test conditions. Does it really surprise you that driving a car faster than the EPA test lead to lower results, all else being equal ?

Like Fuzzy, my experience has been with my last 3 cars that if I drive about 55 mph my results are quite close to CAFE -- about 20% higher than the middle range of the EPA sticker.

Who wudda thunk ?

 

Also, for dstrauss, Hybrid drivers complete run for mileage mark was done utilizing Pulse and Glide plus Warp Stealth in the Prius II for maximum FE … - CleanMPG Forums.

There's also SHM (http://priuschat.com/forums/gen-ii-...y-mode-alternative-65-75-mph-range-hints.html) but I found it unsuitable for my speeds and would thus be unsuitable for dstrauss.