22-05-2025
Dr. Diandra: Season's longest race tests man more than machine
The nature of the Coca-Cola 600 has changed since its inaugural race in 1960. Back then, 600 miles was a test of mechanical endurance. Cars were set up so close to their failure points that DNFs – Did Not Finishes – were common.
Why 600 miles? One reason manufacturers go racing is to prove that their cars are not only fast and sporty, but also reliable. The 600-mile Charlotte race started out as NASCAR's 24-hours of LeMans. So as we approach this year's marathon, let's examine the DNF rates and how they've changed over the years.
The graph below shows DNF rates – the number of DNFs divided by the total number of cars – from 1960 to 2024. I've purposely not numbered the individual bars so you can better see the overall trends. I will, however, point out a few cases of interest.
In the inaugural 1960 race, 70% of the 60 cars – that's 42 vehicles – didn't finish the race.
Only 10 of those 42 DNFs (23.8%) were due to accidents.
Six drivers (14.3% of all DNFs) were disqualified. That included Lee and Richard Petty, marking the only time and father and son were disqualified from the same race.
The remaining 26 DNF drivers suffered equipment failure. Engine-related problems accounted for half of those failures.
Only the winner – Joe Lee Johnson – finished on the lead lap, marking one of his two career Cup Series wins. He led just 48 of the 400 laps and took home $27,150. Second-place driver Johnny Beauchamp finished four laps down.
While 70% is huge for a DNF rate, that first year didn't hold the record for long. In the 1966 race, 33 of the 44 cars (75%) failed to cross the finish line running.
Only three (9.0%) of those DNFs were due to accidents.
Engine-related failures accounted for 24 DNFs (72.7% of all DNFs)
Only 11 drivers were on track for the race's final lap. Marvin Panch won, outpacing G. C. Spencer by two full laps.
Taken as a whole, the Coca-Cola 600 rivals Daytona and Talladega for DNFs. Out of 66 races to date:
Less than 50% of the field failed to finish in 15 races or 22.7%.
Thirty-four races (51.5%) had a DNF rate of 30% or more.
But the graph also shows that the DNF rate is overall decreasing over the years. If we consider only races from 1995 on:
No race has had more than a 50% DNF rate.
Only four races out of 30 (13.3%) have a 30% DNF rate or higher.
In 24 of these races, more than 90% of the field finished the race running.
There were even two years in which only one car failed to finish the race.
In 2009, Mike Bliss' car retired with a vibration after just 42 laps.
In 2021, Kurt Busch's car lost its engine after 139 laps.
The highest DNF rate since 1992 is 45.9%, or 17 DNFs among 37 cars. That was the 2022 race – the first year of the Gen-7 car.
Fifteen of the 17 DNFs were due to accidents, which includes drivers who failed to beat the Damaged Vehicle Policy clock.
Two drivers (11.8% of the DNFs or 5.4% of the full field) had engine failures.
Of the 20 drivers who finished the race, 17 finished on the lead lap.
Denny Hamlin's margin of victory was 0.12 seconds, one of the closest finishes for the Coca-Cola 600.
So while the DNF rate is comparable to some races from earlier times, the reasons for those DNFs have shifted significantly. For one, engine failures are much rarer these days, although Ryan Blaney has managed to have two of them this year already.
One positive for drivers in this long of a race is that they have time to come back from penalties and mistakes if made early enough. In the 2022 race, Kyle Larson crew chief Cliff Daniels pointed out that they were not only the most penalized team (with three penalties), they also crashed and caught on fire. They finished in ninth place.
On the other hand, the three drivers who combined to lead 143 out of 413 laps (34.6%) finished 15th, 25th, and 33rd.
If there is one characteristic this marathon race has retained over the years, it is unpredictability. Consider, for example, recent margins of victory. Since 2001, the time difference between the leader and the second-place finisher has ranged from 0.027 seconds (Jimmie Johnson, 2005) to 10.2 seconds (Kasey Kahne, 2008).
Margins of victory have been closer in the Gen-7 era: 0.119 seconds in 2022 and 0.663 seconds in 2023. Last year's race, of course, was cut short by rain and ended under the red flag.
While we haven't seen any finishes as close as we've had with the previous two generations of car, we also haven't seen a driver run away with the race.
So far.
The race's unpredictability extends to the number of unplanned cautions. (Unplanned cautions exclude any caution known ahead of time, like stage break cautions and competition cautions.) The graph below shows how the number of cautions has varied over the last 24 years, from two in 2021 to 22 in 2005.
That 2005 race was an exception, however. Before 2005, this race hadn't seen more than 14 cautions (in 1980.) That number includes all races that have numbers of cautions reported in Most races had between six to nine cautions.
But Charlotte Motor Speedway 'levigated' (i.e. diamond ground) the track surface before the race. Drivers struggled just to keep their cars headed in the right direction. Multiple spins and accidents slowed the race – although the end provided an exciting, close finish.
That makes the 2022 race, the first race with the Gen-7 car, the most cautions in a normal race. That race had 18 cautions for 90 laps, which means 21.7% of the race was run under caution. Three of those cautions were stage-end cautions. Of the 15 unplanned cautions, there were:
Seven spins
Seven accidents
One debris caution
It wasn't the longest race in terms of time, but it ran 619.5 miles, which makes it the longest NASCAR race in history by mileage.
None of this data helps us predict what will happen this weekend. What I can say is that the Coca-Cola 600 has become more of a test of people than machines. Which pit crew can consistently pull off quick stops in a race that often has the most pitting of any in the season? Which driver can remain focused enough for four-plus hours to avoid making mistakes on pit road and dodge any on-track carnage?
And how many fans will make it through the year's biggest day of racing without needing a nap at some point?
