May 15, Littleton MA

[JethroBodine]

First number was MPG by our guages, mileage corrected MPG, percentage over EPA.

[bwilson4web]

Ah, I see the 'corrected' MPG handled by adjusting the indicated miles versus a fixed, course miles. But I was just thinking about the results and how using the EPA as a handicap impacted the results:

• 1st - 56.3 MPG, 1990 Jetta (EPA changed in 2008)
• 2nd - 101.1 MPG, 2009 NHW20 Prius
• 4th - 55.4 MPG, 2005 Scion xA (EPA changed in 2008)
• 10th - 86.8 MPG, 2010 ZVW30 Prius

Assuming the dealership wants to sell their inventory, where is their reward?

The results remind me of the "Green Human" Portland-to-Portland, 8,000 mile marathon that ended with the Prius being within 1 MPG of the 'winner', the Jetta ... a difference without a distinction. But it is a fundamental problem of any ranking based just upon the vehicle MPG relative to the EPA score ... especially when in 2008 the EPA 'moved the goal posts.'

Chris Hogan at PriusChat had suggested, price-performance, that eliminates the effect of the EPA handicap by bringing in the vehicle payload:

• vehicle volume * MPG => payload.mile / gallon

This would change the scores:

• 5,855 = (87+17)*56.3 :: 1990 Jetta
• 11,323 = (96+16)*101.1 :: 2009 Prius
• 5,429 = (86+12)*55.4 :: Scion xA
• 10,068 = (94+22)*86.8 :: 2010 Prius

This is scoring based upon the vehicle alone, the payload and mileage. It eliminates the EPA handicap that in 2008 gave our 52 MPG 2003 Prius an unearned, higher ranking than our 52 MPG 2010 Prius:

• 104% = 52/50 - 2010 Prius
• 126% = 52/41 (EPA 2008) - 2003 Prius
• 6,032 ft{3} miles / gallon - 2010 Prius
• 5,252 ft{3} miles / gallon - 2003 Prius

For the participants, a great day and nice drive. But for the sponsor, time, money and resources that might have brought in new sales prospect, what did they get? Why would a 2010 Prius owner ever enter again?

The only salvation is a 2010 Honda Insight didn't show up. The EPA 41 MPG would have made for an especially awkward moment.

Bob Wilson

[NeilBlanchard]

I agree that using the 2008 EPA rating makes the Prii look less good, but in absolute terms, every single one of the other cars including the Camry Hybrid -- beat both of us driving ICE powered cars.

So, if we could afford buying a Prius or find an Insight, then we should. I would love to get 60, 70, 80+MPG all the time.

That is why I want to build CarBEN EV -- it will do 200+ MPGe and maybe even 300+.

[Formula413]

Wow, I checked this forum one day too late and missed it, I definitely would have gone

[JethroBodine]

Neil, unless I missed something, we both beat the Camarys( 37&45 to them - 53&57 to us), but I do agree with what you are saying. Every Prius there did do better than us, and I'm guessing, the lowest MPGs from them were from complete rookies, and THAT should be their focus for a sales pitch. I figured( wrongly, as it turns out) that the winner was going to be the best MPG, hence my statment here," If I can beat one Prius, I'll be happy.", and my statement to Wayne just before handing in my Ralley sheet,"You don't have to worry about ME winning anything."

I got the chocolate/peanut butter cup, they were out of mint chocolate chip so my son settled for cookie dough, both larges, and MMMMMM MMM! Good!

[brucepick]

Originally Posted by JethroBodine

Just got back from the Ralley...
...Oh, and, well,... I guess I took first.

First is good!!

[NeilBlanchard]

You're right Jethro -- I had the ~60MPG of the 23rd place Prius in my head for some reason. So, all the Prii beat us in absolute terms...

We have more room to improve, and maybe that motivates us a bit more? I wonder what Chien Lui actually got, since it is limited by the number of digits on the stock display? And of course Wayne Gerdes in the Prius Plugin -- I think he said that he used ~3.5kWh of electricity and ~0.04 gallons of gas? So that is equivalent to ~0.144 gallons of gasoline, so he got ~168MPGe.

[bwilson4web]

We own two Prius, an 03 and 10, and the 03 Prius had the EPA composite mileage change in September 2008 from 48 to 41 MPG. But it was getting the same 52 MPG before and after the change. Yet scoring based upon an EPA ranking gives this vehicle a much higher higher and unearned ranking by 'moving the goal post.'

Another scoring approach is to multiply the MPG times the internal volume to give a utility ranking. This is the cubic feet.miles per gallon, a measure of how much payload was moved a given distance per mile. This chart shows the two scoring mechanisms:

The utility scale was adjusted to overlay the EPA based ranking of the NHW20 Prius.

There were five models in the rally:

• full size sedan - Camry hybrid, lower ranking
• full size hatchback - NHW20 Prius, stayed same
• full size hatchback - VW30 Prius, higher ranking
• compact - Scion xA, big drop
• compact - Jetta gas, big drop

The EPA based ranking gives no indication of the relative size of each vehicle so the Scion xA and Jetta compact cars had a high ranking but small payloads. In contrast, a utility ranking, a type of 'price-performance' ranking, shows how much service each vehicle provided for a given amount of gas without impacting relative driver skill. It normalizes the different vehicles.

A utility ranking also opens up competition for a large volume vehicle with a small engine ... say a delivery or semi-trailer truck. However, this is handled by giving passenger volume a higher weight and clamping the cargo volume to some ratio of passenger volume. This would keep the Camry hybrid from decreasing so much. But in theory, a well design bus (some of the earliest hybrids were busses) could compete. Although I haven't done the math, even motorcycles and mopeds could compete. This type of universal ranking begins to approach the 'seat-mile' used to evaluate flying versus driving.

There is a practical aspect of a utility versus EPA based scale. Imagine you are in New Orleans and have a fixed amount of fuel, a thousand people with suitcases, and need to move them away from an impending disaster. The utility scale allows us to select the vehicles and drivers to optimize the task. An EPA scale would leave people behind.

I know how the historical, EPA scale came into being. Just it may be time to find a scale that is independent of changing, parochial, government regulations and based upon the intrinsic characteristics of the vehicle.

Thanks,
Bob Wilson

ps. Added the spreadsheet if anyone wants to look at alternate scoring ... say mass, paint color, rain drops . . . Ok for those entertained by numbers.

[JethroBodine]

Psst... Bob...My Jetta isn't a diesel

[bwilson4web]

Originally Posted by JethroBodine

Psst... Bob...My Jetta isn't a diesel

Thanks, I didn't know but looking at the score, it makes sense:

• 56.3/225.1% = 25 MPG :: the 2008 EPA number

I'll fix my earlier postings.

I understand in the future it will be "Prius only" which given the sponsor, a Toyota dealership, makes sense. They didn't even get a press release out of it. A more interesting question is whether there will be another one?

Bob Wilson