2021 DNFs: NASCAR by the Numbers

There were 181 DNFs in 2021, down slightly from 2020. Let’s dive into who and where the DNFs happened — and why. As usual, all thanks to racing-reference.info

2021 DNFs by Driver

Let’s start by looking at drivers who ran (or intended to run) a full season.

  • Quin Houff had the most DNFs at 10.
  • Anthony Alfredo came in second with 9 DNFs
  • Ryan Preece was a close third with 8.
  • The numbers drop a bit after that.
    • LaJoie and Stenhouse, Jr. tied with 6
    • Logano, Byron, Newman,Bowman and Almirola all had 5 DNFs

On the positive side

  • Denny Hamlin was the only driver with no DNFs in 2021.
  • Harvick, Larson, Truex Jr., Redick, DiBenedetto and Bilicki tied for second with 2 DNFs each out of 36 races.
  • Honorable mention for Garrett Smithley. He’s not on this chart because he only ran 27 races, but he only had one DNF in those 27 races.

Of top drivers:

  • There’s a clear correlation between rank and DNFs: Not finishing a race is obviously going to impair your points total; however, finishing doesn’t guarantee a higher rank.
  • Joey Logano had the most DNFs of the top-8 season finishers with 5
  • Champion Larson had only 2 DNFs

All Drivers

Expanding the scope, let’s look at all 2021 DNFs. Because drivers ran different numbers of races, I plotted percentage DNF.

Eight drivers who ran only one (or two) races DNFd all races they ran. While some of these drivers are new, there are a couple of veterans on that list as well. But these are really small numbers of races, so there’s a lot of chance factored in.

Among drivers who ran five or more races

  • Justin Haley, who will be full time in Cup next year, has a 25.8% DNF rate over 31 races.
  • Cody Ware ran 32 races and had a 21.5% DNF rate.
  • For comparison, Quin Houff’s DNF rate, which was the highest of full-season drivers, was 27.7%

DNF by Track

Our 181 2021 DNFs give us an average of 4.8 DNFs per race, but — as you might expect — 2021 DNFs were much more likely at some tracks than others. You would think superspeedways would be the most likely places for DNFs. You’d be partially right.

2021 DNFs by track shown as a vertical bar chart

While Daytona took the first and second place honors in this category, Talladega was 11th (fall) and 13th (spring).

  • Daytona, with a total of 32 DNFs accounted for 18.4% of all DNFS in 2021.
  • Texas came in second with 13 DNFs
  • Road courses accounted for 38/174 DNFs in 2021, or 21.8%
    • But the numbers varied a lot. While the Indy road course had 12 DNFs, Watkins Glen only had 1.
  • Two out of the top five DNF tracks were new to the series this year. (I know we raced in Nashville before, but that was a LOOONG time ago.)

2021 DNF Reasons

It’s interesting to examine the reasons for DNFs given that they’ve changed a lot over the years.

Any slice without a number is less than 1%; dvp=damaged vehicle policy

This year, crashes were the main reason for DNFs at 67.4%, If you add in dvp — cars that were retired because they were damaged and could not be repaired to spec within the time allotted — accidents and subsequent fallout account for 71.8% of DNFs.

Engine failures still account for 11.6% of all DNFs. In absolute numbers, there were 21 engine failures this year.

Historical DNFs

The number of DNFs has change over time, as well as the reasons for those DNFs. Let’s look first at the absolute numbers from 2001 to 2021.

Although there have been some variations in car counts over the years, they can’t account for the variations in numbers. As I noted earlier this year, the start-and-park phenomenon had big implications for DNFs around 2004 and 2012.

DNFs 2001-2021 By Reason

Breaking the DNFs down by reason in terms of percent also shows the shift in reasons for DNFs.

You can see from this chart that engine failures have gone down quite a bit as a DNF cause, but that the trend isn’t headed for zero. While engine failures are far less likely today than in the past, as long as teams are pushing the limits, there will still be engine failures.

Crashes but have been as low as 23% and as high as 75%, but the numbers aren’t increasing or decreasing. They’re oscillating. DNFs were about as prevalent in 2008 as they were in 2020, but there were a bunch of variations in-between those years.

Crashes and engines are the two DNF reasons that are immune to any effect from start-and-parkers, so I’ll limit my comments to those.

And that’s your 2021 DNF report!