just read sept. could you get more info on jeff dean's cng truck? would love to get 38 to 50 mpg.  

http://www.delucafuelproducts.com/
Marc can get you setup.
I am working on a CNG/Propane/Hydrogen injection article for November.
With CNG the most important piece is the tank. They range in price from $500 to $3,000 based on the material they are made from.  Keep an eye on ebay. Carbon fiber ones are the lightest. Metal ones are heavy. Propane tanks are cheaper because it is not pressurized as high.  

CNG is a relatively cheap fuel if you compare its GGE (Gasoline Gallon Equivalent).
Remember to add the CNG MPG with the diesel MPG to get total energy used.
Here are some good sites for references:
www.dieselforum.org
www.doe.gov  

Propane is pressurized at 200 psi and CNG is 3600 psi range. Double check these figures.  

I've been to Bangladesh and they use CNG more than anything. So does Pakistan and Iran and etc.  

Me too!  Sign me up and I'll sell my Jetta Tdi as I did my Golf Tdi when I bought my '07 Leramie MEGA cab 5.9L w/6spd auto and 4" from the turbo back!   What would it cost to install, ball park, I wonder?!?!  

Am i reading this right 50mph. Where do i sign. I dont even care how much it is. I want it ROFL  

Keep in mind...you still have to run it in conjunction with diesel. I don't think you can run a diesel on straight CNG. The buses running CNG have been converted with new heads with spark plugs. Still, impressive mileage if true.  

Westport
http://lngtrucks.westport.com/faq.php
LNG
Diesel SPark Plug  

jason.thompson:
Westport
http://lngtrucks.westport.com/faq.php
LNG
Diesel SPark Plug

So it's still a "dual-fuel" engine. Cool, though.