Am not an Car Expert. But yeah after a driving of 7500 kms I am writing my expreince with my own Alto 800 LXI CNG car.
The car interior quality is not so good. Once you switch on the AC and if you switch off the AC after some time than the car will full of odor.
Fter driving the 7500 kms the front and rear glass are making noise. Even after complaining to maruti showroom they replied that this much noise is normal. But this is abnormal for any car. Ou need to do recertification of your CNG cylinder every 3 years(As per Indian Govt. Norms).