Fuel Hoses Lines/piping And Fittings problems of the 1999 Volkswagen Golf

Smell of gas heavy inside the car. Smell equally as bad if windows are rolled down. Gradual decrease in the miles to gallon. Took to dealership while under warranty. They replaced the fuel component that sits under the passenger side of back seat. Happened again one year and 1 month later. Car then out of warranty. Took to private mechanic. Fixed problem again. Told both times it was repaired that a cigarette on the road way could have cause car to explode due to gas spewing out of car. On the component that had to be replaced (im not sure of the exact name) there was a plastic "nipple" that comes out of component and a plastic tube is attached there. ""nipple" had cracked almost completely off and gas was spewing out every time I pressed on the gas. Car was driven normal and not involved in any accidents. Perhaps dry rotting of plastic?.