Exactly.The supposed discrespancies between real-world and EPA occur because of driving conditions and driver behavior -- period. There is no unaccounted for motive power. It's not a case of creative accounting.

I live in Albuquerque, which is not a congested city, and I drive non-aggresively and do my best to time red lights. Outside of winter, I always get > 60 mpg in city driving, and typically around 65. My wife routinely gets < 55, and not infrequently < 50. Really, there is no mystery here.

 

That's exactly what the problem is, however. The test is started with a fully charged battery pack and there is no requirement that it be at the same level at the end of the test. From what I've read elsewhere, the pack is about half depleated by the end of the test, thus you don't see the effects of lost assist and forced charging, both of which would have pulled down the scores a bit. The only way to "fix" that would be to run the test for a very long period or to tell the manufacturer it must maintain a certain battery level at the start and end of the test.

 

AZ, I don't think that is true.

I'll look for a reference later.

 

On what basis do you make that last sentence?

troy

 

Look at this page:

http://www.fueleconomy.gov/feg/fe_test_schedules.shtml

It's obvious from looking at the test methodology that the Prius test allows an unlikely real-world scenario, thus the overly high 60 City number, which VERY few drivers achieve, and certainly NO ONE can achieve by just driving completely normally, unless by chance their commute happens to mimic the EPA test almost to a tee..... Average speed 20 MPH, with 23 stops....Duh....

We all know it's a flawed test - even the EPA admits it. Full hybrids are rated higher because of the extra time on electric and thus no carbon emissions... .

 

The tests are JUST as flawed for conventional cars. The ONLY use for the EPA numbers is for comparing car to car differences, there's no point in expecting the FE of what the EPA measures for any vehicle.

In the real world you will sometimes drive around and end up with less battery level than you started out with, so once again the tests may reflect what can happen in the real world.

I agree they should change the tests, especially in light of their own measured discrepancies between real world and tests, but that goes right across the board, not just for hybrids.

 

Not really......Here's why not....

If a Prius drives 31 minutes, averaging 20 MPH, the MPG will be WAY SKEWED HIGH because of the use of the battery to drive the car, thus creating ZERO carbon emissions when the car is in electric mode. That's a HUGE advantage for the Prius in *THAT SPECIFIC SMALL TEST* which WILL NOT bear up over the long haul of a tank, unless, like I said, your normal commute mimics the test almost exactly.

If a conventional car (say a Camry) drives 31 minutes, averaging 20 MPH, the car will emit carbon the ENTIRE TIME, meaning the MPG will be more realistic to stretch over the entirety of a tank.

So, yes, the test is flawed for both, but MORE flawed for the HEV because of the time spent emitting ZERO carbons. See?

 

I see what you are saying, and I can see how that would skew the results somewhat, but it's actually quite hard to make a Prius use up all it's battery under that type of driving. More often than not the gas engine will come on to generate electricity so that the battery is not used at all. If you activated EV mode (not available to the EPA) then, yes it would be easy to drive around and use up the battery in a few minutes, no problem.

A bigger reason it may seem skewed is the amount of time spent idling -- a Prius will definately have a huge advantage there, whereas in real world driving people may not idle nearly as much, making it seem excessively high when compared to real world numbers.

The only real way to determine how skewed the tests are is the battery level difference, and there's no data at this time, as far as what I've seen. It would be interesting to know, for sure.

 

I don't know anything of the sort. I think 60 mpg is a reasonable EPA result. I get 60 or greater, *with* AC. Look over the database here at GH for non-winter months, and then see if you still think 60 mpg is a rare bird.

Saying the car runs in EV, which skews the result, is simply false logic unless there is an unaccounted for powerplant. I found G1 Prius testing by the NREL using the EPA city route. Their end battery SOC was 3% from initital. Since the battery is good for about 3 km of all EV driving, and the SOC is held within a 40% range, we are talking about a gain from the battery of about 200 meters, on a 17,000 meter course. All told, maybe a 0.5 mpg 'steal' -- IF the SOC always ended lower than it started, which is unlikely.

 

When the vehicle is run in EV mode, the carbons are zero, right? So ANY TEST which forces the car into EV mode MORE THAN it would be in EV mode in the REAL WORLD is a faulty test, correct?