[ProfBerta]

I usually have a long freeway commute, 90 miles round trip, and average 51 MPGs. But I'm on summer break right now and taking mostly short trips. My MPG has been hovering between 40 and 45. On a normal car, I wouldn't be surprised, but I thought the Prius was supposed to get better MPG in the city, like 60 or more? What's going on?

Roberta

 

[efusco]

I usually have a long freeway commute, 90 miles round trip, and average 51 MPGs. But I'm on summer break right now and taking mostly short trips. My MPG has been hovering between 40 and 45. On a normal car, I wouldn't be surprised, but I thought the Prius was supposed to get better MPG in the city, like 60 or more? What's going on?

Roberta

"City" is a very vague word. If you drive in a "city" that has a traffic speed, distance and stop/go pattern exactly like that of the EPA tests you'll do just as well or better than the EPA est. of 60mpg. But, if you run AC, have lots of stops and go's and accelerate to speeds higher than that of the EPA tests ands slow down faster than the EPA tests or have lots of stops where you shut down then restart the car, etc. you're going to get significantly lower than the EPA estimates.

The bottom line is that it all boils down to speed, distance, driving conditions and your personal driving style. I might be able to get 60mpg in your 'city', but I may also get just 40. In a different "city" you may get 65mpg.

 

[Tideland Prius]

I think when they mean 'city', they mean suburb. I certainly get better fuel mileage travelling within the 'city' but my mileage drops the moment I hit downtown. Traffic lights and every block + traffic will burn the battery down.

Also, as with any car, short trips will kill the mileage. But, with the Prius, if the car is warm, it'll take less of a mileage penalty.

 

[Lefty]

I can get great mileage in city driving, but only if it's a pretty long trip. Unfortunately (for mileage) we live very close - about a half mile or less - from most of the places we shop etc. Those short city trips are definitely mileage killers because the prius never warms up. I'm considering moving much farther away from the shopping areas just so I can get better mileage. :wink:

 

[FlyingJoe]

One thing that would distinguish Prius' city-driving gas mileage from any other car is that a lot of the time the car isn't moving and, contrary to every one else, the engine is off.

When not moving, then no miles or kilometres are being accumulated but any other car would be burning gas, and lots of it. I know that I am saving mucho litres of fuel when 'driving' all day in the city, but a significant portion of the savings doesn't get credited in the math of miles per gallon.

So I don't sweat the city driving mpg rate...

 

[evander]

I do live in a suburb, and I've never hit 50mpg. As a matter of fact, my mileage drops into the 40's consistently as I drive around my village. I leave home, hit a stop sign, accelerate, stop, reach another stop sign, and so on for 10 minutes when I stop the car. Then the procedure starts all over again. Unless I travel along the highway, expressway, or for longer distances on larger stretches, my mileage is never over 43mpg. However, I've noticed that cruise control does increase mpg noticeably. Of course, my car supposedly "isn't broken in" yet as I've not had even my first oil change. So there's still hope to reach the nirvana of 50.

 

[kirby]

I get about 52 mpg in my local '02 Prius. I think the reason for that is that we live in a very hilly area. Thus, I get to use the electric power quite a bit, and recharge it for "free" going down the hills.

 

[mrv]

short trips kill fuel economy in any car. short trips is not the same as the EPA "city" cycle.
(BTW: for about the first 5min (or longer) of any trip from a cold start, the Prius will run its gasoline engine to warm up emissions componets and such to proper operating temperatures, so if you have a short trip where you don't get very far out of the warmup, you'll have poor fuel economy.)

I'm not sure if the EPA city cycle is the Urban Dynamometer Driving Schedule (UDDS) aka LA4 (city test cycle): http://www.epa.gov/otaq/emisslab/methods/uddsdds.gif
or if it's the Federal Test Procedure (FTP): http://www.epa.gov/otaq/emisslab/methods/ftpdds.gif

(Highway is: Highway Fuel Economy Driving Schedule (HWFET): http://www.epa.gov/otaq/emisslab/methods/hwfetdds.gif )

As taken from: http://www.fueleconomy.gov/feg/info.shtml#estimates

<blockquote>
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 vehicle models to confirm manufacturer's results. 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).
</blockquote>

Chances are, you don't drive like the tests...