Well, 300 kilometers is about 186 miles. A lap at Nashville Super Speedway is 1.41 miles, so that's about 132 laps, give or take. The best lap time of the winner of the Pro-IT race at last year's event was a little over 1:13, but a conservative time might be 1:15 per lap, which would be 160 minutes, give or take. Add a couple of 5 minute pit stops and you are at 170 minutes, so it's around a 3-hour race.