First off...RC fuel isn't related in any way to hydrocarbon fuels that you use in regular cars or SUVs. Diesel is a hydrocarbon fuel...gasoline is hydrocarbon fuel.
RC cars, at least the two-stroke compression ignition types, run on alcohol-based fuels...made of a mixture of methanol (or ethanol) and nitromethane (basically oxygen-supercharged alcohol).
In terms of typically measured emissions (HC, CO, NOx and CO2), alcohol-based fuels are quite environmentally friendly and are made from what are basically the byproducts of oil or coal processing. Using them as a fuel creates some nasty stuff, but not in great quantities and not very persistent.
There's NO WAY that we're gonna run out of alcohol-based fuels and there aren't any emissions requirements or concerns regarding them. You can make suitable fuel out of all sorts of stuff...they're really cheap, really clean and you can make them from renewable resources.