The Hyundai Eon LPG is the cheapest gas car and the Toyota Innova CNG is the most expensive gas kit car currently. The Chevrolet Aveo, Hyundai Accent, Maruti SX4, Wagon R, Eeco CNG are also cars with Gas kits on them.
Yes you can get it installed. But we won't recommend it . Since, it will void warranty. CNG is best suited alternate fuel option instead of LPG. However, there are no CNG filling stations available in Faizabad UP. The nearest one is in Lucknow.
We would not recommend a CNG kit on Brio for it doesn't have a lot of low end torque in the first place and the kit makes it worse. On CNG, it will require a lot of throttle input to get it going in the first and second gear. Hence, we would not recommend you to get CNG kit fitted..