2018 IMSA WeatherTech Data – The Rolex

(image credit: Morgan Rhodes)

The 2018 Rolex 24 at Daytona is now in the past and was a race full of surprises. With 50 cars on track the average person would have expected a lot of contact between cars, cars blowing up, getting stranded on track, spinning and other issue that normally bring out cautions, but that was not the case. This years race was a record-setter in terms of the number of laps ran and distance covered. In 2018 the overall winning car covered 808 laps for 2876 miles and an average speed of 120 miles per hour. Comparing this years race to all the post-merger races the GTD class winner ran more laps than the overall winner did in any previous post-merger race.

The track for Daytona has changed since I started doing these analysis’. Sectors 2 and 3 form the infield and will show a cars acceleration and handling capability. Sector 7 is the bus stop chicane, which will show strong braking and cornering capability. Every other sector is all about power and top speed.


In GTD, we saw 4 different manufactures occupy the fastest 4 laps. The Ferrari’s and Mercedes seemed to hold a slight advantage. The Ferrari’s along with their Italian rivals from Lamborghini were the strongest through the speed trap. The Mercedes and Audi struggled for top end speed but made up time through the twisty bits. The Audi’s were especially quick through sector 1, which runs from the start finish line to about pit out. Despite being down a few mph through the speed trap they were able to get through turn 1 very well. Overall the entire GTD class can only be described as “stupid close”. When looking at average lap time the entire field is covered by 1.1 seconds and when looking at average speed, worst to first is 4.4 mph with the majority of the field being covered by about 3 mph. Pretty damn impressive.

Now, doing a quick comparison of the Rolex data and the Roar data we can get a picture of how cars improved or didn’t improve. In GTD only 3 of the 4 cars to improve on their times from the roar were Ferrari’s. Meanwhile, the Lamborghini’s and Lexus’ were all slower than their lap times at the roar. Through the speed trap, the BMW, Ferrari’s and Acura’s seemed to find some straight line speed.


In GTLM the fastest three cars on average lap time were the 2 Ford GT’s followed by the Ferrari from Risi, who actually set the fastest race lap. The Fords held a slight advantage everywhere and posted quick sector times just about everywhere. They were quick through the twisty bits while the Corvettes were able to more or less match their paces through the flat-out sectors. The Porsches and BMW’s struggled all weekend, especially the BMW M8. With the only new-for-2018 GTLM car they were about 2.5 mph down on straight line speed and were about .2-.3 slower through the infield.

When looking back at the roar, both BMW’s picked a lot of time, along with the Ferrari. The Fords ran about the same pace they did at the roar along with the Corvettes. The Porsche’s lost a little bit of time from the roar. The entire field, with the exception of the two Porsches, picked up considerable speed through the speed trap.


And now for the prototype class…it was basically an all DPi show at the front of the field with the quickest LMP2 spec car being the #23 Ligier down in 9th. The Cadillac’s, Nissan’s and Acura’s all seemed to be pretty close on pace. The Nissan’s had a small advantage through the power sectors while the Cadillac’s were quicker through the twisty bits. The one car that continued to struggle was the Riley/Multimatic. The struggle for the updated Riley/Multimatic is odd, but most likely comes down to driver lineups. The car has received a ton of updates but went significantly slower than last years cars. Last year the prototype cars average lap times in the 1:36-1:37 range. This year, everyone was in the 1:38-1:39 range. The entire class (excluding the Multimatic/Riley) was within 1.7 seconds and was within 2.5 mph through the speed trap. Despite what the Racer comments section or the numerous Facebook groups will say, the entire class was pretty damn close.

Comparing things to the Roar, there were not huge changes. The Acura’s found a little bit more terminal velocity while the Cadillac’s went the other direction due to being BoP’d.


With the amount of green flag running we can get a better idea of what the pit stops looked like. The first set of graphs shows the number of pits tops and the amount of time each car spent in the pits. In general, the cars that finished first spent the least amount of time in the pits.

When it came to pit stop length it’s a similar story. The Cadillac’s ran a max stint length of 25-26 laps with an average stint length of 22-20 laps. The Acura’s were able to run a maximum stint length of 30-32 laps with an average stint length of 22 laps. Across the class it seemed like most competitors were able to run anywhere from 25-30.  GTLM cars were able to run about 30 laps with the Ford GT’s being able to run a few laps more than that. Keep in mind that the average stint length is affected by things like unscheduled stops, penalties and other things. And even the max pit stop length can be affected by rain or yellow flag periods.


One of the big story lines in the last couple hours of the race was the ticking time bomb of an engine in the #5 Cadillac DPi. The pace slowed considerably…enough that the 54 and 31 were able to get 3-4 laps back on speed alone. Its clear in this chart that at around lap 650 the #5 car began to slow. They went from running 1:39’s to 1:41’s and then onto running consistent 1:44’s. while the 31 and 54 were chasing them down running 1:38’s and 1:40’s.


The Last thing to look at is individual driver speed. The following plots show 2 columns. The blue column is the average of the fastest 10 laps for each driver. The yellow line is the gap compared to the fastest team mate. (click for bigs)

About the author


Ben Wedge (@TheBenWedge) is our tech guru who focuses on data analysis, engineering and all things nerd. By day he’s a mechanical engineer and by night he’s a..well he’s still a mechanical engineer, but also dives into anything automotive-tech related. He is also a Cruisin’ USA afficionado.

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