Thanks for proving MY point.
Your Alto 'SURVIVED' 190,000km before it had to get its rings done. And there is a significant difference between a 'surviving' car and a 'running' run. Trust me, if you had used petrol instead, it would have gone to 400000km atleast.
One of my friend installed CNG in his R18, his engine got over at 60000km. Where as a PW member has clocked 4 lac km on his same model R18 on gasoline and its engine is as good as new.
On paper MAYBE CNG burns cleaner and runs smoother, but PETROL is what our cars need and what are they designed to consume. Honda Motor Co. wasnt stupid enough to design a all new CNG engine for Civic GX which runs great on CNG but donot has Petrol as a second option.
P.S
FF CNG in Alto/Coure/cultus means NOTHING. Its just another gimmick by our local manufacturers to increase sales. Toyota Indus had to modify the headers and rings of the current corolla XLi to make CNG init more 'bearable'
And lastly, if your CNG theory had a little truth, then companies like Honda, Toyota, Audi, Mercedes, BMW, VW etc wouldnt be spending MULTI BILLION DOLLARs in an hunt for a more fuel efficient engine for their blue efficiency/Hybrid vehicles which run solely on PETROL. Otherwise they can throw a cylinder in its trunk too to make it 'fuel efficient or cost effective'
The new E250 is 1.8l super charged with around 200 horses and guess about its performance? It does 20 km/L! And this is what you call R&D! And iam glad they didnot threw a cylinder in its trunk or maybe they would have if your cng theory had some stones.
Rocket science eh?