well i have benn driving a cuorw cx eco since the last month, and i am impressed by this small wonder...hehe
i will recomend you eco caz, there is quiet a lot of difference in after market cng and stock cng, it has timing adjuster, or insimple words you can say advancer, whihc work wonders, very good drive (no knocking) on both petrol and cng. it has 50 litre cylinder, after market has 40 (mostly) and as far as i know the cylinder is of faber therefore lighter and bst of all no warranty void.
the last two cng refills were 214 and 210 rupees and gave a milage of 152 and 150+ km's within city respectively, and this include rush hour driving also.
now the choice remains of cl and cx, as far as i know the differnce is ac, colour choices, and a couple of small things.. well ac works perfectly fine in cuore and if you want ac than buy cx, dont buy cl and then after market ac....
thanks