POMS - Percent of max speed

POMS normalizes lap speeds across track. The POMS for any given driver’s lap is the average speed of that lap divided the fastest lap of the race - hence, percent of max speed. It assumes that the fastest lap of the race is the theoretical fastest lap anyone could have driven on that day at that track. You can then average that number across all green flag laps of the race to see who was, on average, the fastest in the race.

However, you can already do that without POMS. You can already take the average speed of every driver in a race and compare them safely (check out the laps list of a race for the data), because everyone is driving the same track at the same time. You will, though, find it challenging to compare Martinsville laps against Talladega laps, as Martinsville laps are topping out at 95 mph while Talladega laps can average over 200 mph. POMS takes care of this by comparing against the fastest lap in the individual race. A lap that scores 0.96 at Martinsville is relatively faster than a lap that scores 0.94 at Talladega, and thus more valuable for winning races, even if it’s 100+ miles per hour slower.

We can then average POMS for a driver across a variety of splits across a full season and see who was most, on average fastest within those splits, treating each race as even. For example, Chase Elliott led the NASCAR regular season in POMS in 2020 (predicting his championship). Had we simply taken the average speed of all laps, short tracks would have been wildly underweighted and super speedways overweighted due to the relative differences in their speeds.