The Ergosphere
Friday, October 07, 2005

Immediate responses: Revive the PNGV

Up until about 4 years ago, the USA had a program to develop ultra-high mileage vehicles.  The goal of the Partnership for a New Generation of Vehicles (PNGV) was to produce full-size passenger cars achieving 80 miles per gallon.  Prototypes such as Chrysler's ESX-3 were achieving 72 MPG at a projected cost premium of roughly $3500.  Delivery of the first production models was set for 2008-2009.

This program, on which about a billion dollars had been spent, was cancelled by the Republican majority.  As a consolation prize, we got... another research program, but aimed at hydrogen vehicles.  This effort is not projected to yield cost-competitive vehicles for another 15 years or more, and the viability of hydrogen vehicles is questionable when natural gas (the cleanest feedstock) is plummeting in production and skyrocketing in price.

There ought to be a groundswell of support for bringing back the PNGV.  Amazingly, there are people involved in the energy discussion who have never heard of it.  This boggles my mind.

The PNGV could have been a strike, but it was mis-thrown by the right and wound up as a gutter ball.  Is it time for a letter-writing campaign to our legislators, newspapers, and others to at least try for a spare?

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"full-size passenger cars achieving 80 miles per gallon."

OK. That is very interesting, but can they do it. A Honda Insight gets 65 mpg, but it is not what I would call full-sized. Is it even theoretically possible to get that kind of mileage?
The ESX-3 achieved 72 MPG back in 2001, so there's an existence proof for being able to get within 10%.

I'm of the opinion that 80 MPG is feasible, with the caveat that it's on the old EPA driving cycle.  IIRC, the trick is that the engines in the PNGV cars are not just diesels, but adiabatic diesels with turbocompounding.  The greater energy content of diesel fuel and the greater efficiency of the engine puts 80 MPG (and perhaps more) within reach.
You have to wonder how much cheaper and efficient these exhaust turbines would be coupled to an electric generator rather than mechanical linkages.
If you look at the front and the interior, the car appears much wider than a Prius; it seems to be in full-size or at least mid-size territory.  OTOH, I see that I misremembered the cost premium.  (I wonder how much of that was due to Li-ion batteries, and would be much smaller today?)
A couple more ESX-3 links:

The Intrepid ESX should be able to get the claimed fuel mileage figures. Compared to the Prius, it's running a turbocharged, tubrocompressed diesel versus Prius' gasoline engine. Also the ESX-3 had a curb weight of 1020 kg versus 1320 kg for the Prius.

I don't know how large the battery pack for the ESX-3 was but the ESX-1 was carrying 180 lbs. of Pb-acid batteries.

The 2nd link I posted contains this warning that I skipped over to get to the stats:

"Evan Boberg, in his book Common Sense Not Required: My Career With Chrysler, wrote that none of the hybrid vehicles described here lived up to the specifications given by Chrysler."
Interesting note regarding the book, but nothing states how badly the claims miss the truth.

A full-size car which got 60 MPG, or even 50 MPG, would be a huge improvement over the status quo.  Given what consumers are willing to pay for an SUV to haul people, even a $7500 premium might well be acceptable a couple years from now.
I did a bit of poking around, and found this list of claims:

Chrysler ESX3:  72 MPG
Ford Prodigy:  > 70 MPG
GM Precept:  80 MPG diesel-electric, 108 MPG fuel cell.

If the ESX3's performance was greatly overstated, it was either just an attempt to keep up or a shared delusion.
" Is it time for a letter-writing campaign to our legislators, newspapers, and others to at least try for a spare?"

I'd say yes! Forget fuel cells and EVs, in the short-term, increased performance IC engines are so much more feasable if we actually want to see a real reduction in our transport fuel consumption.
Funding (properly used) will accelerate development.  A company which grows by capital accumulation is going to grow more slowly than one which sells stock, issues debt or gets grants.  In the case of systems which have large economies of scale or are competing with others which have such economies, a lot of money may be required to get things going.

What's really important is for government NOT to provide unfair competition for the developing technology (subsidies, mandates, or preferences for counterproductive systems).
I am still very skeptical. I found some of the materials that the other commenter found. Interested readers should checkout this article from the SAE.

One thing that struck me is the claim that the ESX3 weighed 1020 Kg. The SAE article says they used light weight plastic. It does note the special seats. Did the thing have a roof liner? spare tire? etc.

The lightest weight production car (not a mini or smart car) that I know of is the Audi A2, which is not imported. I found a spec sheet It weighs 990 Kg. But it is not a big car at all. It is 150' long (Mini Cooper 140) and caries 4 passengers. The A2 is made out of aluminum and has a CDx of 0.25. The A2 is powered by a 1.4L diesel, non-hybrid, and is rated at (EU) 49/74 mpg ( the numbers on the site are imperial). I wonder how much you could improve those numbers by hybrid technology. 25% for the urban cycle?

The A2 is a very nice little car, but its size class has never been accepted in the US. Further it is really kind of slow for American traffic, although it might be ideal for an urban runabout.

A "Full size" car, i.e. one that is about 200' or 5 M long is going to be a lot heavier. The lightest car in that class is the Jaguar XJ which is all aluminum and weighs ~3700 lbs. (~1700 Kg). The all aluminum Audi A8 weighs 500 lbs more and is 100 lbs more than the Mercedes S. Part of the extra weight is the Audi's 4 wheel drive system.

My 2002 Honda Accord, which is a mid-sized car (and perfectly adequate for most uses) weighs ~3000 lbs ~1360 Kg. In all aluminum you might be able to get it down to 1200 Kg, but you would need a more powerful motor than the A2 or the ESX3 to make it attractive.

All of this is flopping around in the dark. We need to understand what the fundamental physics and economics of this project are. How heavy does a an automobile of a given size have to be (and yes insulation and air-conditioning are mandatory)? How much energy does it need to take it around a typical days worth of driving? What are the realistic possibilities for an engine? how efficient can it be?

I don't know the answers to these questions, but I will wager that Audi and Honda a pretty close to the edge of the practical.

As a final note we should remember that just as important as efficiency is the miles driven. That in turn is a function of land use patterns, school systems and other political issues.
Good links there.

Ultralight construction tends to use panels of strong skins over a foam or honeycomb core.  This also insulates; it's the "secret" behind Structural Insulated Panels (SIP's).  Stiffness goes way up too.

Mileage is an issue, but I don't think that it's going to kill anything if a car that pleases the masses only gets 60 MPG instead of 80.  The real radical improvement is going to come from plug-in hybrid systems, and it may even be worth sacrificing some of the weight savings to incorporate the larger batteries required.  A car that only gets 60 MPG running on the sustainer but covers 75% of its mileage on energy from the grid gets an effective 240 MPG; compared to that, a boost from 60 MPG to 80 is small change.

Bigger batteries allow bigger motors (more power without using the engine) and better regeneration.  These things cascade.

I'll wager that Audi and Honda have a notion of "practical" which is tied mighty closely to profits.  If they'll make more money shaving a bit of economy for some cost reduction here or a bit more customer appeal there, they'll probably do it.  Decisions like these are driven by market conditions; change customer demand and you'll change the kind of car you'll get.

Unfortunately, land-use patterns, telecommuting and the like are beyond the scope of the auto designer's job.
I strongly encourage you to mail me with such things instead of posting OT in threads.  Mail's in the sidebar for just that purpose.
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