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Discussion Starter · #1 ·
Hello to group-just joined.
Not that i am complaining, but when I use my Prius in cold weather on short trips (3 miles or less) the gas mileage hovers around 25 or so.
During warm spells (we occasionally get them here on the Cape) mileage goes up to figures reported by others in the group, so I know there is nothing wrong with the car. BTW, i got my '02 Mica green in November am still in love with it - now I wish I had bought one sooner.

Discussion Starter · #2 ·
I am in Potsdam, NY with a 3 mile commute, my milage is about that in the cold (cold here is anything below 10) but anything above 10 I notice the first increase to about 30mpg, at aroud 25 it gets around 35mpg, above 35 I go up to a bit over 40mpg. And yesterday when it was above 55 I was in the got about 48mpg. Overall I am happy with the car and am starting to figure out how much the mpg is effected by the weather.


Discussion Starter · #3 ·
I don't know if this matters but I have found that turning on the front defroster or otherwise demanding heat from the system causes the gas engine to run.

Discussion Starter · #4 ·
> I don't know if this matters but
> I have found that turning on the
> front defroster or otherwise
> demanding heat from the system
> causes the gas engine to run.

Makes sense. When I turn up the thermostat in my house I notice the furnace turns on. When I turn up the thermostat in my Prius I notice the engine turns on. The gas engine in the Prius is the furnace.


Discussion Starter · #5 ·
yes to all - The Prius was designed to keep the pollutants down and not to worry as much about the mileage. That means the engine is completely warmed up prior to any shutdown and electric running. Obviously in cold weather and short (<10minute) trips , the car will never be totally warmed and therefore you will get nowhere near the EPA numbers. The EPA only tests on completely warmed up vehicals. That is to keep things equal for all tests.

Keep in mind the EPA numbers are for comparison sake only and depending on your type driving , the numbers will vary lots..


Discussion Starter · #6 ·
JUst for comparison I don't think the hot/cold effect is any different than on a non-hybrid car. As an example, I also own a 99 Buick Regal with the 3.8 litre V-6. The EPA rating is 20 city / 29 Hwy. I usually get between 28 and 32 on a long trip driving at approx 75MPH on interstate. Now as for local Urban driving I average about 20 or 21 in the summer, but in the winter I only get about 16 or 17, and if I drive less that 3 or 4 miles and it's well below freezing or 20 - 25 degrees the milage will be less. I believe the general rule on ICE powered cars is anywhere from 50% to 75% of Hwy ratings for city driving and the variation would be dependent on the outside temperature. Just my personal thoughts! Also, I would guess if the Non Hybrid cars would be equiped with a Monitor like the Prius has, A lot of drivers would raise their Eye Brows!

Don Good

Discussion Starter · #8 ·
No one seems to dismiss the results of the old Prius expected MPG calculator, so I'll repost it here. Just remember that the defroster (full windshield, maybe floor/windshield too) runs the AC compressor at OAT greater than 32F. The AC is run off of the gas engine, so you'll see more starts there. Also, in the first 5-10 min. or so of driving, the Prius is working hard to get the emissions system up to operating temps, so the Prius will sacrifice MPG (by running the engine) in order to keep the SULEV status at all times of the driving cycle.

From: "Chuck Gibson" <[email protected]>
Date: Mon Jan 15, 2001 9:44 am
Subject: Prius Mileage Calculator II


To estimate what your average mileage might be, start with 45 mpg and make the following eight adjustments:

1) Percent of trips (from cold start) less than ~10 minutes:
0%:+2, 33%:+0, 66%:-4, 100%:-8 (consider an EV)

2) Percent of time AC or defroster on:
0%:+1, 33%:+0, 66%:-1, 100%:-3

3) Outside temperature:
below 10F:-9,10-30F:-6, 30-50F:-3, above 50F:+0

4) Percent of time spent in crawling stop'n'go traffic:
0%:+0, 33%:+1, 66%:+2, 100%:+4(consider moving)

5) Percent of time using techniques to maximize Prius mileage (i.e. gradual
start on electric, then quick cceleration on gas, then foot off gas pedal when cruise speed obtained):
0%:+0, 33%:+1, 66%:+2, 100%:+4

6) Do you drive very aggressively? (i.e. jack rabbit starts, speed >> average traffic speed):
No:+0, Yes:-3

7) Are your tires under inflated?: (less than 35psi front, 33psi rear)
No:+0, Yes:-2

8) How many adult equivalents does your Prius carry on average?:
1 or 2:+0, 3 or 4:-1, 5 or more:-2

Add or subtract these values from 45 mpg to get an idea of what mileage you might get. Feel free to interpolate. Remember: Your Mileage May Vary (YMMV).

I have based these factors on my 3300 miles in a Prius, plus the polls,
studies, and messages in this and the Yahoo site. Comments or
suggestions welcome.


Discussion Starter · #9 ·
Found on my window sticker (near the big gas pump icon):

"Actual Mileage will vary with options, driving conditions, driving habits and
vehicle's condition. Results reported to EPA indicate that the majority of
vehicles with these estimates will achieve between
44 and 60 MPG in the city, and between
38 and 52 MPG on the highway."

See <> for a brief description of how the EPA gets their mileage ratings. Note that the highway test is done using a warmed engine, and that the city test is done in 68-86F outside temperatures...

How are fuel economy estimates obtained?

The fuel economy estimates are based on results of tests required by the U.S. Environmental Protection Agency (EPA). These tests are used to certify that vehicles meet the Federal emissions and fuel economy standards. Manufacturers test pre-production prototypes of the new vehicle models and submit the test results to EPA. . EPA re-tests about 10% of the tested vehicles to confirm manufacturer's results in EPA's lab. The vehicles are driven by a professional driver under controlled laboratory conditions, on an instrument similar to a treadmill. These procedures ensure that each vehicle is tested under identical conditions; therefore, the results can be compared with confidence.

There are two different fuel economy estimates for each vehicle in the Fuel Economy Guide, one for city driving and one for highway driving. To generate these two estimates, separate tests are used to represent typical everyday driving in a city and in a rural setting. Two kinds of engine starts are used: the cold start, which is similar to starting a car in the morning after it has been parked all night; and the hot start, similar to restarting a vehicle after it has been warmed up, driven, and stopped for a short time.

The test used to determine the city fuel economy estimate simulates an 11-mile, stop-and-go trip with an average speed of 20 miles per hour (mph). The trip takes 31 minutes and has 23 stops. About 18 percent of the time is spent idling, as in waiting at traffic lights or in rush hour traffic. The maximum speed is 56 mph. The engine is initially started after being parked overnight. Vehicles are tested at 68 F to 86 F ambient temperature.

The test to determine the highway fuel economy estimate represents a mixture of "non-city" driving. Segments corresponding to different kinds of rural roads and interstate highways are included. The test simulates a 10-mile trip and averages 48 mph. The maximum speed is 60 mph. The test is run with the engine warmed up and has little idling time and no stops (except at the end of the test).

NOTE: To make the numbers in the Fuel Economy Guide more useful for consumers, EPA adjusts these laboratory test results to account for the difference between controlled laboratory conditions and actual driving on the road. The laboratory fuel economy results are adjusted downward to arrive at the estimates in the Fuel Economy Guide and on the labels seen on new cars, light trucks, and vans. The city estimate is lowered by 10% and the highway estimate by 22% from the laboratory test results. Experience has proven that these adjustments make the mileage estimates in the Fuel Economy Guide correspond more closely to the actual fuel economy realized by the average driver.


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