lpg kits are approved via govt of india. UNITAX is best bec its cheaper kit and isi approved only cost 9000rs from 900cc to 1500cc vahicals + 2500rs extra for government approval on your RC.
u can install lpg kit in any patrol car.
etios is just a entry level sedan in Australia ppl do lpg conversation on almost every high end cars like ford falcon holden commodor toyota camery etc. bec lpg is cheaper.
and 100% taxis run on lpg I had a toyota Rav4 fitted with Lpg converson kit.
Both Toyota Etios and Swift Dzire are good options, while the Etios has space, Swift certainly has a powerful engine, better interiors and after sales services. The Dzire also enjoys better resale value.