Possible Clues:

• 400 meters, maybe
• Quarter mile, at many tracks
• 2.5 miles, at Daytona
• 2.5 miles at the Indy 500, e.g
• Full circuit
• 2.5 miles, at the Indy 500
• Single trip around the track
• Track unit
• Quarter-mile, for many tracks
• Up and back, in a pool