As I was driving at 55mph on the hwy I started smelling gas. I thought it was the car in front of me so I was just going to pass him, but quickly realized I did not have the power to pass another car. So I pulled over on the highway and got out of my truck and noticed flames dripping from the center of the vehicle by looking at the front driver wheel area. I tried to put out with a fire extinguisher that a bystander had given me, but it was just too late in the truck was engulfed in flames.