Have not seen anything lately on the Hydrogren Gas "circus". Some love it; some not so much. I have read a bunch on the net and viewed lots of videos on YouTube. Seems to me there are two distinctive steps in getting better performance and economy from HHO. 1st-make the gas (safetly). 2nd-play with your "effy" and engine control system to trick it into letting you get the better performance and economy. If anyone is working on one of these projects, sound off & share your findings. If EVERYBODY got 50 mpg, our world may be a bit better. I have an '04 Camry 4-cyl with 120K miles that I may modify with HHO.....maybe.
1SG

 

My own opinion is various energy companies want to retain their energy distribution system setup (refiners/gas station) and hydrogen is a better fit then something more readily available such as natural gas.

If a home owner already has NG going to their home it is possible for them to install a compressor to convert this to CNG to fuel at home.

Unfortunately at this time the government, utility company, CNG conversion kit makers have so many restrictions and costs that is it cheaper in the long run to continue using gasoline or diesel.

For a time Toyota made CNG Camry's for California only around 2000. Below is some info on the car:

Fuel Economy of the 2001 Toyota Camry CNG

If you looking for more unique cars (fuel efficient) look overseas. Toyota even made a diesel powered Camry.