According to all car dealers on jail road, CNG can be succesfully installed in Toyota Passo because it has a special race wire which is not present in Vitz. According to my opinion, one should avail the opportunity to install CNG in Passo because its petrol consumption is 9 km/ltr on petrol and 18 km/kg on gas. I personally have passo and will be installing cng next week or so, inshaAllah