For the next two laps, Earnhardt and Jarrett were racing almost side-by-side.

For a second they were racing side-by-side like a team in harness.

The duo raced side-by-side through the corner and down the front stretch into the first and second turns.

Late in the race, the two raced for the lead side-by-side before Keselowski bumped Busch during a pass.

Downhill Double Dipper is one of the world's only side-by-side racing slides.

It believed these changes would promote more exciting, side-by-side racing.

First, the Pontiacs had never been raced before, so no one knew how the strain of side-by-side racing for 100 miles would affect the tires.

"I think the cars handled bad enough Sunday where there wasn't too much side-by-side racing," Labonte said.

The first side-by-side racing started in 1935.

The two horses raced side-by-side for several strides, but Galileo then pulled ahead to win by two lengths.