Roger in the US wrote: I am assuming this is in soles since the gasoline prices are quoted in soles.
Yes, the price is per liter and the "symbol" for soles = S/.
So a liter of Propane and CNG is about the same S/. 1.57
CNG comes from Camisea (in the jungle) though a long distance pipeline. Until 2012 the liter of CNG was even cheaper about 0.9 to 1.15 , but the promotional price of CNG is over and actually CNG and propane cost almost the same..
You can identify CNG as its initials in spanish GNV - Gas Natural Vehicular..