Fuel economy system for an internal combustion engine

Would this be safe, practical and efficient? It makes sense to eliminate the whole liquid fuel system in favor of one that carries a chemically correct mixture to the intake manifold, but what happens when it backfires? I think fuel injection and wideband oxygen sensors have the vapor thing covered. How could the method of fuel delivery allow an engine to run leaner? This is definately interesting though . This would be a good one to send in to mythbusters