Poor Mileage in 2007

From what I understand, the mileage will increase as the tire breaks in.

 

It's easy to forget that the 2007 Prius is only rated 45 mpg on the highway from the EPA when you look at the revised 2008 numbers. You beat the EPA!

If there's no problem with the car at all, I recently did two big second gen Prius fuel economy posts on my blog. If you scroll down on the right to "Prius mileage tips" under keywords they're currently the first two that will pop up. There's one about Hobbit's style of driving specific to the highway.

Forgive me if this stuff you already know, I see you have a lot of posts

 

How fast were you going on that trip? How fast was the wind?

 

+1

It is hard to travel 800miles in or through California without hitting some serious elevation changes as well.

Plus you have brand new tires. They require a break in period so most of your 800 miles would have been part of the break in period thus lower mpg.

The GenII has no problems getting 48-52mpg on a flat highway and cruising along at 65mph or less.

 

If you lowered your speed on the trip your MPG's would increase.

 

Bob Wilson posted some MPH vs MPG charts a while back. One of them has Gen II data at high speed, and the data point at 70 MPH is 47 MPG.

http://priuschat.com/forums/gen-iii...4296-updated-mpg-vs-mph-chart.html#post917520

 

I see some difference in MPG between 65 and 70 MPH. But still you should generally get little bit more than that, like 50 MPG in hilly conditions (at least that's what I get in my 2006). When I change oil, I have noticed that my MPG drops for the first two tanks or so, not sure why.

 

There's the problem.

 

Hi All,

Rest needs to read Hobbits stuff on 6X mpg at 6X mph. Above about 64 mpg, the Prius cannot drop into warp stealth, and your basically driving the car as if it was a standard car, with the engine always turning over, fuel injecting/burning, and the transmission at a fixed ratio.

Various people have done prius PSD gearing on-line aps which show this clearly. Look at this link: Toyota Prius - Power Split Device . Set MG2 to a 64 mph. Set Engine to the 1000 RPM - the warp stealth RPM, and you will see that MG1 is spining close to the max negative limit of -6400 rpm. If you up MG2 to 65 mph, that negative MG1 limit is exceeded.

So, if you travel above 64 mph, the car cannot enter warp stealth, and it continues operating in a engine-on mode. This does not mean you cannot exceed 64 mpg. Going uphill, keeping it around 20 HP in the BSFC mound, no problem if you get over 64. But when you crest, you need to be back down under 64 to get into warp stealth. Otherwise your idling your engine down the hill, for no good reason. Hobbit (and others) report 60 to 65 mpg using this technique.

Now, this works for hilly terrain. Because in flat terrain at these speeds, you quickly exceed 64 mph at the BSFC mound power levels. And you cannot store energy into vehicle speed, effectively, due to aerodynamic non-linearity. But, in a hilly terrain, you can store energy into vehicle altitude , with the engine at a good BSFC point.

With Hobbit's technique one drops down to under 64 mph at the crest of a hill and gets into warp stealth. Now the engine is off, but turning over at 1000 rpm, from electricty being generated by MG2, and fed to MG1.

 

Hi Rest. Under the right conditions I can get 60 MPG at speeds around 40 to 50 MPH, but at 70MPH I'm down around 47 MPH also. I'd say you're going ok considering the relatively new tires.

 

Hi Donee,

I am probably not following the Hobbit trick ...
Are you saying the fuel economy advantage is gained from having the ICE turn at a lower rpm some of the time ?

 

Yep, sounds right to me too. I manage about 50 mpg at 70 mph, but the difference is explained by the thinner air where I live.

 

Hi Sage,

Let me start over. The fuel economy is gained by using the engine at optimum BSFC (best efficiency) to store energy in moving the car higher in altitude, then not burning gas downhill. This results in low enough losses to get good mileage. To get the car in warp stealth for the downhill glide, you, when you crest the hill you need to be 64 mph , or less.

In warp stealth, the car is not burning gas, but the engine is still turning (through electrical power).

 

Donee,
I apologize for being dense, are you just pointing out that ICE use downhill is unlikely to be in an efficient range ? That makes sense to me, but how about driving on a flat with constant ICE use ? Any fuel economy lost ?

 

Are you being sarcastic? As pointed out, you beat EPA for your vehicle- with brand new tires. 47 mpg, is not "Poor" mileage.

 

"The right vehicle for you" depends on the problems you are trying to solve or the needs you are trying to meet. If you want to minimize petroleum consumption, then certainly an EV such as the Leaf is the answer. If you want to minimize global warming, the answer may be something else. Minimize total cost of ownership or operating expenses, something else yet again. What do you want a car to do?

 

When I lived in the SF Bay Area, my lifetime average was ~46 mpg. I did manage an "tank" above 50 mpg by keeping my speed down on the highway below 70 mph, the whole time. When I was newer, I too was wondering if it was me, my driving, California conditions, California gas formulation, etc. I posted at http://priuschat.com/forums/gen-ii-...commute-w-little-opportunity-pulse-drive.html.

Regarding short trips, that kills mileage. I now live in a much colder climate and now just have almost all short trips. I'm lucky to break 40 mpg on a tank, but this isn't surprising to me at all. (I average only ~13-17 mpg typically on my Z now whereas I'd get ~21-23.x mpg when I was in the Bay Area.). Most fuel-efficient cars is what CR got on the 2nd gen Prius. Last page of http://www.consumersunion.org/Oct_CR_Fuel_Economy.pdf describes their test procedure vs. the old government one.

I don't know if you ever read http://priuschat.com/forums/other-c...uth-about-epa-city-highway-mpg-estimates.html. It was very insightful.

As Chevy Volt is only EPA rated 35 city/40 highway, 37 combined in charge sustained mode. As for Honda Leaf, there isn't one. There is the Nissan Leaf.

Since you're in CA, your electricity is likely expensive. You might be curious to see http://priuschat.com/forums/chevrol...olt-in-their-long-term-fleet.html#post1280607. Although you'd end up reducing your use of oil (or making it 0 w/the Leaf), you might both are costlier to drive than a Prius due to high electricity costs.

As for "But here we are in the 21st Century and the majority of vehicles still don't average over 50 mpg", unfortnately, per Power Search, if you exclude EVs in your search and look for 2010-2011 models w/combined mileage >50 mpg, there are 0. The only one that gets 50 mpg combined on the EPA test is the 3rd gen Prius.

We definitely have an issue w/car size, weight and power bloat. See Minicars? I don't See No Stinking Minicars - Column - Auto Reviews - Car and Driver and the executive summary at Light-Duty Automotive Technology, Carbon Dioxide Emissions, and Fuel Economy Trends: 1975 Through 2010 | OTAQ | US EPA.

Yeah, the 1st gen Insight was the mileage king. Too bad the CR-Z and Insight II were such disappointments.