With so much CNG in the USA- I am dumbfounded as to why CNG-powered vehicles are NOT ubiquitous on our roads!

Picken's plan (which is far from perfect) calls for a massive shift from foreign-oil based transportation to domestic-CNG based transportation.

Hey, more money stays local (God knows our economy needs it) and less goes to our buddies like: Ahmedenijad and Hugo Chavez. (btw- Hugo's latest is inviting the Russian military to play in our back yard)

Where are all the CNG-refueling stations?

The near future for Natural Gas (methane) promises a fantastically renewable fuel, especially for metro areas, where organic matter, such as food & fecal waste, is concentrated. Both of these waste streams, when decomposed without oxygen, produce methane. This idea of waste equals food/fuel is a premise of sustainability, astutely outlined in W. McDonough's classic, 'Cradle to Cradle'.

@Alex: Yes, emissions reductions are critical and CNG/LNG delivers, especially in the area of fine particle pollution, the bane of many metro areas, natural gas reduces fpp vehicle emissions to nearly zero. Definitive info @
http://www1.eere.energy.gov/cleancities/afdc.html

Except CNG AND Gasoline (dual use) means nearly no cargo area except in very large vehicles. Also CNG refueling terminals are basically non-existant (unless a local taxi fleet owner is willing to let you fuel up at their station).

Natural gas at the house + some type of refueling station (at home) meets some of the same problems as a pure EV in that you have to go home to refuel.

If you make a dual fuel vehicle you end up compromising on one or both fuels and have a less efficient engine overall. I bet a 3.5L tuned specifically for CNG could get better gas mileage and horsepower/torque (maybe at a cost of higher NOx emissions than the present tuning provides).

I think our #1 priority as a nation should be to get off foreign oil, and I want to do my part. I also like the fact that the exhaust pollution (that which causes SMOG and respiratory problems, not CO2) is less than a hybrid. Does anyone know how much that kit costs and how much it costs to get it installed?

JMartin makes good suggestions. CNG is best suited for fleet buses near term. Better if they are supplemented by high cycle batteries in a hybrid drive trains. The lithium titanate NanoSafe batts and competitors are best but a test of Zebra might be good. These buses can then be recharged at route end points - increasing AER and dramatically lowering fossil fuel consumption.

The problem with CNG conversion for light duty vehicles is they must meet strict safety standards mandated by DOT and EPA. There are very few certified CNG conversion shops around today for this reason and those that are will charge in the $8-12K range for certified (without which vehicle is un-insurable) converts.

Dual fuel cars have been around for a long time. CNG can be integrated into a vehicle with many small tanks. There is not any theoretical weight advantages for large pressure tanks. You can even make yuor own NATURAL gas, methane that is, from all kinds of waste material including sugar bought from a local store. ..HG..

The problem with CNG is that is finite. Trading one finite source of energy for another would not lead to a solution. Our natural gas resources provide the U.S. a way to ease off of gasoline by powering larger fleet vehicles and equipment that need the power electricity cannot provide. I thought the article about using computer modeling to test emerging technologies for consumer vehicles viability was promising. A great deal is lacking from our understanding of resource flows for materials use in making the next generation of consumer vehicles. It is the stroke before midnight. We cannot afford to make the wrong choice. Be mindful of what you preach.

Niel Young's LinkVolt has a natural gas rotary engine (mazda) serial hybrid installed in a 1959 Lincoln. Gets 70 mpg apparently.
http://linkvolt.com

130 octane fuel and a 3.5 liter engine to move an Impala!! Not the optimal solution.

Another news flash, certified CNG conversions as of last year quotes for 6 cylinder engines run from $10k - 15k per vehicle. Insurance costs increase also. BUT, in some States there is a tax credit of up to 50% conversion cost. So you could get this Impala conversion down to $5k per vehicle.

The other caveat is CNG availability in your area. There are several web sites that track CNG stations according to zip code. Unfortunately for many of us driving 40-50 miles to the nearest CNG pump does not make eco-sense.

And then there's the conundrum that replacing gasoline with non-renewable fossil CNG, is a troubling choice for greens.

I think the ultimate vehicle (end game) is a PHEV powered with CNG and small liquid fuel tank (gasoline or E85). Such a vehicle can be powered with electricity, natural gas, biomethane, gasoline or ethanol. Liquid fuel allows the vehicle to work with extant infrastructure while NG filling stations are added.

Leave biodiesel to our trucks and aircraft.

Some vehicle design is needed to accommodate space needed for tankage and battery packs.

All-electrics have only a niche market unless and until they can be recharged quickly, which is probably technically infeasible.

Hydrogen is hopeless.

We should work toward developing the here and now viable, instead of pipe dreams.

The selling point for bi-fuel vehicles (gasoline/CNG)is that they provide peace of mind during a period where CNG refueling stations are scarce. Working for a gas utility promoting NGVs, I must admit I was dead set against bi-fuels. Many public and private fleets using CNG can tell you that their drivers - if not under threat of disciplinary steps - would always use the gasoline. With the recent run-up in gasoline prices, that was no longer a concern. There will be a day when gasoline and diesel will climb again in price...never to return to today's prices. Then, when it means significant savings, you will see natural gas flowing like water.
Although it's a little nit picky, I would say that natural gas (methane, at least)is, technically, a renewable fuel. Microbial organizms found in shale recently have demonstrated they eat shale and pass methane gas. And, although seemingly impossible to harvest or produce, methane hydrates are estimated in quantities that are astounding: some estimates are 3,000 years supply of methane.
I agree with the cargo space issue when it comes to extended range packages. This is simply because no carmaker selling vehicles in North America have taken the time and spent the money to build a platform desinged for sufficient CNG storage tanks. They cram tanks onto existing platforms. The funny thing is that they are willing to design completely new cars for EVs. Trunk space (and bed space on pick-ups) should be considered sacred to maintain.
I'm happy to pontificate further, but fear I'm boring most everyone.