37mpg City?

I agree about the hills, do a google maps or mapquest map Akron, Ohio to Windsor, Virginia. I make this trip frequently. And this past one about 3 weeks ago we averaged 53 MPG on the way down (the wife was driving about 75 MPH on I-270 and I-95 in the DC and Richmond area. The wife stayed an extra week to visit her mom because I had to work. So it was just me on the way home and I got 54 MPG to give you an idea of my average speed I made 2 stops at rest stops to go Pee and a third to stretch my legs and get a quick bite to eat. 514 miles and it only took me just over 8 hours including the 3 stops and still got 54 MPG and the hills are unbelievable for 50 % of that trip (PA and MD). Its all about technique.

 

The hills will really hurt your mileage. I don't think you answered the question about how long (in time) your commute is. Short trips on any car kills mileage.

Again, what was your previous car and what did it get during the same commute?

As I stated in my earlier post at http://priuschat.com/forums/fuel-economy/45005-37mpg-city.html#post589834
"Consumer Reports got 35 city in their testing (see ConsumerReports.org - Most fuel-efficient cars). The most efficient non-hybrid automatics listed there are the Yaris and Honda Fit on which they got 23 and 22 mpg respectively. The rest of the ones lower on the list in overall mileage were all manuals, all with 21-23 city mpg."

That would make the Prius ~52% more efficient in the city than the most efficient non-hybrid automatic they've tested. Not good enough?

 

The OP's commute sounds very similar to my wife's daily routine taking the kids to school.

Start a cold Prius, 6 miles of city driving (lots of stoplights, traffic at 30 mph, fairly flat), then a 2 mil climb (gain around 1000 feet, traffic moving at 40+ mph), reach school, turn around to descend the hill and through the city stuff to get home. In the afternoon, restart the cold Prius and do it again.

I've done this drive a lot too. Through the 6 miles city part I can get in the 40s mpg, but the climb is killer, can only get 16-18 mpg while keeping up w/ traffic. On the return, the descent doesn't make up for the climb because I'm forced to burn up the potential energy through braking (if I coasted the whole descent, the Prius would be going >100 mph).

95% of the Prius' miles are on this route and we get 43-45 mpg summer (70-80F, OEM tires) to 35-37 mpg winter (35-40F, snow tires). I've found only about 3-4 mpg difference between my wife's mpg (she drives it like a normal car, no thought to fuel economy) and mine (driving carefully). On trips outside of this daily commute, e.g. driving on the freeway, I get so much better mileage. My conclusion after 1.5 years with our '07 is - steep hills are bad and steep hills with stoplights really suck.

So, original poster, if you have a commute anything like what I'm describing, then you can probably eke out a couple more mpg with more driving technique, but don't expect to get really big mpg numbers.

I don't mind. Our Range Rover was delivering maybe 10 mpg on the same commute.

 

My '06 Prius gets 54 MPG in city with the A/C on. The car has 30,000 miles on it now, but when it was new I didn't get more than 37-45 MPG. As everything broke in the milege went up. However, I don't get more than 50 MPG on the highway @ 70 MPH.

 

If you set the cruise at 70MPH and don't adjust it you can get 49 - 51 with out any technique with tires inflated at 42fr 40 rear. If you can stand to drive a bit slower it inches up.

 

What I don't understand is, how can the computer's estimate be so far off? Mine says I got 54 mpg for a tank, but I really got 40. I only ran it down to half a tank, but still, the computer is way off to this point. Car only has 212 miles.

 

Read up on the fuel tank and how the fill level will vary from tank to tank because of the bladder system. You will find that the MFD is extremely accurate.

 

Thats good to know. I wasn't so dissapointed with the mileage as I was the innacuracy (so I thought) of the MFD, seeing it is brand new. So if you're saying I really got 54 mpg, then this car must be the best thing since squared bagels.

 

Just how much can the bladder tank fluctuate? Even if It were to be off by 1 gallon, still means I got 50 mpg, not 55. I went 205 miles to 5.1 gallons.

 

lets put it this way, the tank says it has a capacity of 11.9 gallons, but its rare that I can squeeze more than about 9.5 - 10 gallons in it from empty (even with topping off a bit)

 

The volume of the bladder in the tank can fluctuate by quite a bit. According to this document:

http://www.autoshop101.com/forms/Hybrid13.pdf

"At low ambient temperatures the capacity of the vapor reducing fuel tank is reduced due to the resin material from which it is made. If the outside temperature is at 14 degrees Farenheit (-10 degrees Celcius) the size of the tank is reduced by approximately five liters."

Note that 5 liters is about 1.32 US gallons

Additionally, when the dealership "filled" the tank before they delivered the car to you, they may not have gotten it as full as you did.

Generally, you can assume that the display is more accurate at computing MPG for any individual tank than assuming that the amount of fuel you just added is the same as the amount of fuel you used since your last fill-up. Over a large number of fill-ups the variablility gets spread out and computing MPG by dividing miles traveled by total miles driven can be more accurate.

There are some regular posters here at PriusChat who have recorded both the displayed and the hand-computed MPG for hundreds of fill-ups and they usually report that the displayed MPG runs about 2% to 5% better than long term computations.

 

I don't get it. i've had my 07 Prius Touring edition for a year, 11k miles, and i've never got better than 42 mpg (on an 1100 mile trip to FL). I average 38-40 mpg. I love my car, but am not satisfied with the mileage (was hoping for high 40s at least based on 60/50 sticker). i do not push my car, but i will not coast and baby it to get a couple mpg. i like to drive, and part of the reason i love my car is that it is responsive & fun to drive.

 

I've been constantly getting 54 mpg stated on the mfd. Hopefully that is correct.

 

37.4 here...Most of my driving is stop and go...Downtown Chicago..

 

Still don't understand why mileage dips with rain and cooler weather. I'm down a few mpg since temps dropped back into the 50s.

 

Rain = more drag on tires
Cooler weather = longer warm-up time for ICE

 

Multiple reasons. I suppose a wet car might reduce the aerodynamic shape a bit. Water on the car increases the weight of the car. Even small amounts of water on the pavement increases the rolling resistance requiring more energy from the car to overcome. Then the car expends additional energy throwing water off the tires up into the air. Another factor is that rain is frequently accompanied by wind which can significantly reduce your MPG. Typically driving habits change in the rain causing more stop and go traffic. Every additional instance of using the friction brakes will reduce your MPG as well. The air tends to be more humid during rain, so if you are using the Climate controls in your car, it may need to use more energy to dehumidify the air for you. There may be other reasons, but these are all I can think of right now. Any one of these reasons is likely to have too small an effect to typically notice. However, the accumulation of all these reasons can add up to a noticeable effect.

 

Re:Rain, cooler temps.

Never affected any of my other cars.....

 

Re: Rain, cooler temps.

Well, how do you know? Did you have a scangauge or other monitor in your other cars on a day to day basis? Or did you average out the rain over a whole tank? Does it rain for 250 miles, or a whole tank of gas where you live ?

Also, a 10 percent change at 20 mpg is 2 mpg, versus 5.5 mpg in a Prius.

Rain has mass, so the density of the fluid flowing over the car is allot more than in dry air. The water either collides directly, or is flung over the top of the car.

I find, that blocking the top grill slitts helps allot with rainy FE on the highway. The water will come straight in there, and cool off the radiator by evaporation at highway speeds. That is where the air/water flluid is being thrown upward, and of couse water being more dense will not change direction as fast, and goes right into the upper grills. And that is where the radiator is the hottest, so it evaporates the water. Which results in the engine thermostat opening wider, and dissipating more engine heat. Kinda like running the heater at 100 F, if not more.