My apologies if this seems a bit harsh but I am curious why you are not more interested in the Euro standards?

I'm not trying to be mean as much as wondering if you'd take a look at the Euro protocol(s)?

Bob Wilson

Repost of http://priuschat.com/forums/other-c...uth-about-epa-city-highway-mpg-estimates.html.

I just thought it was an interesting article, that I came across on Autoblog. I didn't realise it had been posted already!

The UK Vehicle Certification Agency writes about our tests here. You can see from their graph that the test is a lot more artificial than the EPA tests which appear to have actually been recorded from real-world driving at some stage. That chart doesn't show the required gears for manual-transmission cars, but each segment dictates which gear the car should be in.

As you can see, the testing is all relatively low speed. There's only an acceleration to 75mph, a short hold for a few seconds, then a long deceleration, right at the end. We desperately need higher-speed tests to reflect what drivers do. Which? magazine (equivalent to Consumer Reports) adds a constant 70mph segment to the mandatory tests, under the same conditions, which drops the 2G Prius from 65.7 to about 56mpg.

As near as I can tell, the numbers quoted are straight off the rolling road, with no compensation (the EPA reduces the city figure by 10% and highway by 22%). It's more scientific, but you're a lot less likely to get the quoted figures. The test results are actually recorded in litres per 100km (L/100km) and rounded to the nearest 0.1L/100km. This rounded result is then converted to miles per imperial gallon for the UK market, since we're the only ones still using legacy units. (Petrol is sold in litres, so an mpg display is pretty useless.)

The Gen 2 Prius got a figure of 65.7mpg; the MFD is showing 62.2 over the last six months. My calculations are closer to 60 for the same period, but I've had some tanks come out over 63. My last tank was a short fill (pump cut off early) which skewed the figures somewhat - it came out at 71.3! Lifetime average is 56.9.

My previous car, a 2001 Ford Focus 1.6L with 5-speed manual, got 40.9mpg on the test. My spreadsheet says my lifetime average was about 37.8mpg.

You might enjoy this graph, plotted by overlaying the velocity profile:


Reading that the Ford Fusion had increased the 'hybrid mode' speed to 47 mph, I noticed this put the Fusion above the two, middle speed segments in the "extra urban" cycle. The ZVW30 threshold is 46 mph so both hybrids should return excellent results in the Euro tests. As for the accuracy of the USA EPA tests versus actual user reports, well that will always remain an interesting challenge.

In 2007, the EPA revised their testing to be "more accurate," which means the 2003 Prius went from EPA 48 combined to 41 MPG. My 2003 Prius combined MPG is running over 52 MPG over 70,000 miles ... bad car, bad bad car. Although the ZVW30 is not hurt by the revised EPA testing, it really has socked it to the Honda Insight:

The Insight EPA rating is 41 MPG but the user averages are running 50-51 MPG (my chart is a plot of averages, not the total miles and fuel.) The ZVW30 numbers are much closer to the EPA values.

Bob Wilson

Irony of ironies:
It was no small part on the Prius, that caused the EPA to revise MPG standards a couple dozen months back. A decade ago, almost NO one made a stink about corporate SUV fleet vehicles designed to run on grain fuel OR gas ... a 'slight-of-hand' scheme whereby you could get your 18mpg land barge rated at 30mpg. How? Instead of calling a 'gallon' of fuel a 'gallon' ... you mix it (for example) 50/50 with grain fuel ... and only count the 1/2 that's gas. Thus, your 18mpg guzzler now gets 30mpg. Why not 2x 18mpg? Because grain fuel gets worse mpg's. These are your elected/appointed officials shoveling the mountain of B.S. on the public.

Enter $4.00 and $5.00 per gallon gas and the Prius. The Prius got snapped up ... waiting lists ran for weeks and months. The folks that finally got their Prius jumped in ... headed for the fast lane ... SLAMMED the pedal to the metal. Enter 38mpg. Wahhh! :Cry:
The outrage began ... "FRAUD" they cried, "class action" they shouted. So legislators forced more realistic epa ratings ... to the chagrin of Land barge sellers. Their pathetic mpg went down, just as high mileage car's mpg ratings went down.

The mpg stickers say, "your mileage may vary" ... old standard or new standard. Still ... folks scratch their heads and wonder about the variables ...
stop & go driving
short trips
AC
sub zero
hauling large loads
believe it or not ... your mileage will vary

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