Will take 5 - 7 years, it will happen, you can wash a pig, and put earrings and lipstick on it, but its still a just a pig. Diesel along with its dirty brother Coal is the EPA's pig.
Bingo. Once in awhile there are pump and dumps so always short the spikes.
Sentiment: Strong Sell
Natural gas engines also emit PM and NOx, albeit less than diesel, but still require emission control technology. CDTI (ECS) have technologies for use with engines powered with both LPG and CNG.