Advantages and disadvantages on petrol and LPG operated vehicals in maruti 800 and omini in detail?

' We are planning to buy vehical/s for line sales.We shall be carring about 200 Kgs.articals(light weight) plus the weight of driver and a sales man. In all, the load on vehical will not be more than 300/325 Kgs.The vehical will be running around 200 t0 250 k/m in ren hours.This is being the situation which vehical would be more priferable / economical and viable for us.Whether we should go for petrol operated or gas operated one.What are the advantages and dis advantages in both versons, and whether gas operated vehical's engine will have more repairing cost after use of about an year? '