oil is now a bonus resource units don't need it but you need it to build auto plants etc to build tanks, ships and air units
All resources should become strategic resources so that they can be traded. All copies of resources should provide a yield created by means of a dummy building in each city, called ''resource harvester" or something to that effect, with the resources maintaining their on-tile yield increases to emphasize the importance of good city location - this should in fact be increased from its current level. The dummy building should also create the dummy resources of Food, Production, Gold, etc. created in equal quantities as the corresponding yields and providing the same yield, in order to enable the yield trading idea discussed earlier. Food per citizen and the quantities in CivVGameSpeeds.xml should be doubled to account for this.
Resource quantity should also be local, with each city only gaining access to the resources which it is connected to by road or has within its city radius. Food, Production, and Gold should be made usable by additional dummy buildings costing 1 production, given names such as '10 Food' (a building which would obviously cost 10 Food strategic resources and give some number of tile yield (upgradeable based on distance to the sources of Food, technology level, and whatever routes connect the cities. A decay mechanic for the resources of Food, Production, etc. excluding Gold should also be added in order to ensure that major cities are not moved too far away from the centers of production. Foreign trade should also work using this same mechanic. The tile yield dummy buildings should produce +1 gold yet have 1 maintenance in order to allow them to be sold and enable flexibility in the food supply.
Also, implement foreign trade routes which should be required for the trade of tile yield dummy resources and all other resources with other civilizations. It's annoying that such an integral part of history is absent from CiV, much more so given that CCtP is such an excellent mod.