The Honda travels just as far with CNG as if it was gasoline powered.
The following was copied from http://www.altfuels.org/backgrnd/altftype/cng.html
Compressed natural gas is like liquefied petroleum gas (LPG) in many ways, only more so. It is very easy on the engine, giving longer service life and lower maintenance costs. CNG is the least expensive alternative fuel (except electricity) when you compare equal amounts of fuel energy, and, in my experience at least, its price has been relatively steady (except for one big jump when California utility regulators changed the rules!). At the peak of the big gasoline price run-up in April, 1996, I was paying half as much for a gasoline-gallon-equivalent of 130-octane natural gas as I would have paid for a gallon of 92-octane unleaded gasoline! Even with the natural-gas price spikes of the last few years, I have found the price of CNG to be less volatile, and on average lower, than that of gasoline.
"The high octane rating of natural gas allows the CNG-powered Honda Civic GX to use a very high compression ratio and produce more power than stock gasoline versions. My own van has a stock compression ratio and about 10% lower power output than the gasoline version with the same-size engine, but I get significantly better fuel economy on the open road because the high octane rating of the fuel allows timing and mixture to be adjusted for more efficiency without causing detonation ("knocking"). And, as with LPG, because the fuel tanks have to withstand such enormous internal pressures, they are incredibly tough, with good results for safety. In addition, because natural gas is lighter than air and has very narrow flammability limits, if a leak develops it is very likely that the fuel will dissipate harmlessly into the air without causing a danger of ignition or explosion."
the shame of it is the 6 year delay - no reason for that. That's six more years of our money going to the Sand Countries and that nut in Venezuela
My concern runs more to the mundane. Daimler-Benz climbed into bed with Chrysler and the celebrated Benz QC went to hell. If Honda touches that tar baby, will their vaunted quality and dependability go the same way? I’m driving my 9th Honda since 1976, so you know where my loyalty and my concern lie. sd