Onboard refueling control technology has been successfully applied to two vehicles with 98+% efficiency in tests with 10.5 RVP fuel at 84° F. The Onboard system, which controls exhaust, evaporative, refueling, and so called “running losses”, was constructed out of components found in current automotive evaporative control systems. During refueling, the tank vapors are forced into the enhanced charcoal canister by a flowing liquid seal in the fillpipe. The canister was removed from the engine compartment and mounted within the vehicle frame close to the fuel tank. Each vehicle demonstrates a different possible safe location from a crash worthiness viewpoint. In order to further improve safety by preventing the expulsion of liquid gasoline upon gas cap removal, the orifices in the production tank vent lines were removed so that the fuel tank is at atmospheric pressure at all times. As modified, no significant driveability differences from production vehicles were found. Both the production and onboard vehicles met current exhaust and evaporative standards. In addition, results of laboratory simulated rollover tests showed zero fuel spillage.