Im still not using CNG but plan to use CNG maybe after sometime.
Some things i know off are.
1) Ul need to replace rear springs with stiffer ones.
2) The breaks sometimes dont work on CNG, the breaks get hard if the idleing isnt set properly.
3) Some issues would always remain on CNG, ul have to live with them with the cost saving.
FL, The FL package has
1) retractable side view mirrors.
2) Keyless entry.
3) Rear head rests (in some cases).
4) Silvering on door handles and ac knobs. (in some cases).
5) Digital meter.