P1Analysis Study - 2016 Rolex 24 GTLM Corvette Racing #4

This document examines the exciting IMSA 2016 Rolex 24 race at Daytona International Speedway through P1Analysis.com reports for the GTLM class winning #4 Corvette C7.R, the hero car in this analysis.

P1Analysis.com is a web subscription service providing its IMSA WeatherTech SportsCar Championship and Continental Tire SportsCar Challenge race team customers with a set of clear, insightful, and timely post-session reports to help with decision making. P1Analysis currently consists of the following types of reports, produced for the listed sessions.

Report Type Answers these questions ... Session
Session Summary How did your car do in your class? R, P, Q
Race Lapchart How did the ranks of the cars change from lap to lap during the race? R
Race Gaps to Hero How did the time gaps between you and other cars change during the race? R
Lap Time Trends How did every car’s lap times change throughout the race? R
Lap Time Box Plots How consistent and what was the range of lap times for each driver? R, P, Q
Sector Gaps to Hero How much slower or faster than you were the other drivers sector by sector? Also within the hero's make? R, P, Q
Pits and Stints What pit and driver change strategies did each car use? R, P, Q
Pit Lane Times How much slower was your pit service? R

This document describes each of the reports for #4 GTLM hero car and then analyzes the report information.

http://p1analysis.com's version of this document has clickable links to the actual reports and pointers to resources.

Session Summary

The official IMSA WeatherTech SportsCar Championship Race Summary that teams receive, merges all 54 cars from all four classes, P, PC, GLTM, and GTD creating a report suitable for seeing the overall results. While this view is great if you are an official or broadcaster, it is less useful if you are on a racing team where you are primarily concerned about your class's race.

The Session Summary report allows you to quickly see summary information on just the 11 cars in the GTLM class. It additionally reveals per-driver summary statistics.

Note that unlike the official results, all P1Analysis reports are generated from raw timing and scoring data and therefore cannot take into account any penalties or other human updates and corrections that may affect a report.

Race Lapchart

The race lapchart displays the ranks of the cars within your class during a race. By using overall rank on the y-axis, it possible to see both overall and class rank. Furthermore, rough clusters of cars within your class might otherwise be hidden if the y-axis only plotted class rank.

Race Gaps to Hero

The race gap chart displays the time gaps between your #4 hero car and the other cars in your class during a race.


The GTLM race was very close throughout most of the 24 hours, as seen by the very close lines weaving around the winning #4 hero (green) above.

Notice the upper right corner of the chart. Just before the last yellow, #4 (green) was furthest behind 912 (magenta), #3 (olive), #68 (blue), and #25 (brown), but still on the lead lap. Since the chart is a PDF and not a bitmap, you can zoom in on any section.

During the course of an endurance race, a car's lap times fluctuates due to different drivers, pit stops, caution periods, track conditions, degradation, and conservation.

The lap time trend chart scatterplots each car's lap times over the course of the session, excluding pit-in, pit-out, and caution laps. To make sense of the ten thousand or so individual lap times, (LOESS) smoothing lines are created for each car, clearly revealing their lap time trends. Practice and qualifying sessions may not have enough data points for smoothing.

Notice the closing stages of the race at the lower right corner of the graph.

Lap Time Box Plots

In the IMSA WeatherTech and Continental Tires series, each car has more than one driver during a race. Each has different capabilities, particularly in Pro-Am classes like WeatherTech PC and GTD. Box and whisker plots allow you to quickly visualize each driver's lap times.

The lap times used in each driver's plot again excludes pit-in, pit-out, and caution laps. Plots are ordered by each driver's fastest lap time (lowest point on plot, either whisker or outlier) which is labeled. Details on the math behind how box and whisker plots are created can be found at P1TS's Understanding Box and Whisker Plots.


Sector Gaps to Hero

By comparing each driver's sector times, we can see how much slower or faster than the hero car's drivers, others are, sector by sector.

Each panel in the chart represents a driver, ordered by best 1-lap (not pictured) or best 5-lap lap time average (pictured above). The fastest 10 drivers are shown on the top row with the fastest driver on the left. This report is for Oliver Gavin's fastest 5-lap averages. Since the #4 hero car has 3 drivers, there are altogether 6 individual charts.

Oliver Gavin (Best 1-Lap) Tommy Milner (Best 1-Lap) Marcel Fassler (Best 1-Lap)
Oliver Gavin (Best 5-Lap Avg) Tommy Milner (Best 5-Lap Avg) Marcel Fassler (Best 5-Lap Avg)

Within Make

Some WeatherTech and Continental car classes have several cars of the same make. To more easily compare the intra-make race, there are additional reports for the hero's car make.


There is a also companion hero driver table that contains the same information, with sector time gaps are represented in a heat map. Faster sectors for other drivers are colored in green, where gradient shows how much faster.

Pits and Stints

Managing pit stops and drivers changes are important part of endurance race strategy. The pits and stints chart not only makes it easy to review your own strategy, but also study competitor strategies.

This is useful not only during a race, but also during practice sessions to quickly see how competitors chose to make use of their practice session.

There is also a numeric companion table where each row represents a driving stint and information about the pit stop ending that stint. Information includes when (in both time and laps) a driver's stint started and ended, and also pit lane duration as well as what the flag was when the car crossed pit-in.

Pit Lane Times

Many times, a car wins by only a scant few seconds over their competitors. For this particular case, the winning margin was a mere 34 milliseconds. Faster pit service may give a team a winning advantage, so it is useful to examine pit service times. This chart zooms in on the pit portion of the Pits and Stints data above. Data is grouped by stop number, allowing you to more easily compare your 1st, 2nd, etc. stop sequences with your competitors's. For longer races like this one, there can be quite a bit of time "drift" between cars as the race progresses.