Benson moved into the series lead with his fifth victory of the season. He went from 39 points behind to 65 points ahead when Hornaday ran out of gas with three laps to go.
"The minute I saw that, I just assumed it was fuel and I let right off the gas," Benson said.
Benson, Hornaday and Kevin Harvick all made their only pit stops after just 36 laps.
Hornaday, who started on the pole, led every lap before Benson got underneath him in Turns 3 and 4 on the 0.526-mile oval. Hornaday wound up 29th, and Harvick, his truck owner, also ran out of gas shortly before the finish and dropped from second to 15th.
Hornaday said he tried to save fuel all race long, but just came up short.
"We win and lose as a team, so we'll take this one and go on," he said.
Once he saw Hornaday fade, Benson figured Harvick was likely in trouble, too.
"I saw Kevin coming, but I figured he'd probably be close to the same boat," Benson said, adding he never made a victory lap because his truck had just enough gas to finish.
The victory in the Kroger 200 was the first of Benson's career at Martinsville, and gave him a second chance to hold onto the series lead from the front. He had enjoyed a lead as high as 119 points, but a 27th-place run at Las Vegas allowed Hornaday to narrow the gap and he moved in front of Benson last week at Talladega.
"Ron and those guys have been doing a tremendous job and our guys have too," Benson said. "It's making it a very interesting points chase anyway. It's great."
Benson twice held off Hornaday on restarts in the final 20 laps, the last with five laps to go, and was able to take a deep breath and coast to the checkered flag when Hornaday's Chevrolet suddenly began choking on fumes, leaving him weaving down the front stretch.
Hornaday's misfortune allowed Harvick to move into second, but only briefly because his truck also got down to fumes heading down the backstretch and finally ran out of gas in Turn 2.
Fuel issues or not, the right truck won, Crawford said.
"He passed everybody, including me, and it didn't take long when he caught me," he said of Benson, who started fifth. "He clearly had the fastest truck here today."
Hornaday is looking forward to the finish.
"I am glad he won," he said of Benson. "It is just going to make it that much tougher on us. We have four races to go. These guys are up for the task. We are going to run every race like it is the last race and we will go from there. I would rather be behind than in front."
The series moves to Atlanta next weekend.