Aw hell, all you gotta do is get a WOODEN baseball bat, and slip it in between tire/fender. Then as you roll the bat (jammed between the tire and fender) the tire has more grip, so the bat will slide along the steel fender.
You do this at a 45-degree angle. Repeat process a few times, small increments at a time. You may need to have a friend sit on the fender to lower the car (apply pressure) while you roll fender.
You can always do the saws-all trick too... and actually widen the fender...
