Two rounds into the 2023 IMSA WeatherTech SportsCar Championship, let’s address the elephant in the room: Balance of Performance matters.

That’s the most obvious takeaway after the recent 71st running of the Mobil 1 Twelve Hours of Sebring.

To refresh your memory, BoP is the tool used by sanctioning bodies including IMSA and the FIA to create parity between competitors. By mandating incremental adjustments to performance-related items including car weight, engine power, fuel consumption, and aerodynamics – sometimes on a race-by-race basis – the ultimate goal is to have all cars within a 0.5 percent window, expressed as 0.5s over a 100-second (1 minute, 40-second) lap. It’s especially effective in the GT classes, with multiple manufacturers fielding cars with front-, mid-, and rear-mounted engines in a variety of sizes and configurations.

At the Rolex 24 At Daytona International Speedway, the Mercedes-AMG GT3 was demonstrably the fastest car, with WeatherTech Racing claiming the GTD PRO class win in the No. 79 car, and the No. 32 Team Korthoff Motorsport and No. 57 Winward Racing entries showing class-leading speed in GTD. Aston Martin also enjoyed a highly successful race at Daytona, finishing one-two in GTD with The Heart of Racing’s No. 23 Vantage GT3 winning over Magnus Racing’s No. 44 counterpart.

At the other end of the spectrum, the brand-new Ferrari 296 GT3 and the 992-generation Porsche 911 GT3 were well off the pace, as was the BMW M4 GT3. To some extent, that was not surprising, as sanctioning bodies tend to take a cautious approach when setting BoP parameters for new cars. But several competitors, particularly from the Porsche camp, were vocal in expressing their displeasure with the baseline BoP for their new machinery.

Assessing the best Daytona lap time in race conditions for each marque, Porsche had reason for concern, with its best effort some 2.5 percent off the pace set by Mercedes-AMG. The Mercedes advantage was indeed considerable, with only Aston Martin coming within the 0.5-percent target window.

As a result, IMSA made some BoP changes prior to a two-day open test at Sebring International Raceway on February 15 and 16. After lap times and other data from those sessions were analyzed, additional BoP changes were implemented prior to the Sebring 12 Hours, as summarized in the chart below:

The most significant change was a 5mm increase in the Porsche’s air intake restrictor, intended to boost the 911 GT3’s horsepower and straightline speed. More air requires more fuel, so Porsche was also allotted an additional seven liters of capacity. Seven of the participating marques had their weight adjusted (five reductions, two increases) half received different fuel allotments, and Lamborghini also was granted a 1mm air restrictor increase.

The alterations appear to have been successful in tightening the competition, again based on best race lap times, with half of the competing marques within the 0.5 percent parity goal and all 10 bunched within one percent. Mercedes-AMG maintained a slim advantage over the Corvette C8.R GTD, perennially a strong performer at Sebring. Not surprisingly, Porsche made the biggest gains, moving from the slowest car to midpack; Ferrari was another to make a big jump, from seventh at Daytona to third at Sebring.

Of course, individual lap times don’t tell the whole story. At Sebring, both the GTD PRO and GTD results were heavily influenced by a series of late full course cautions, with brought fuel saving strategies into play. In that regard, Pfaff Motorsports’ victory in GTD PRO in the No. 9 Porsche and the 1-2 finish for BMW teams Paul Miller Racing (No. 1) and Turner Motorsport (No. 96) in GTD were undeniably driven by circumstances as the race unfolded.

In GTD PRO, the No. 3 Corvette, which is always strong at Sebring, appeared to have legs on the field. But an unscheduled pit stop to replace a rear shock/damper put it a lap down and the spate of late cautions came too late and too often for the team to recover beyond fifth place

Meanwhile in GTD, Kyle Marcelli claimed a surprise pole in the No. 93 Racers Edge Motorsports with WTR Acura NSX GT3 Evo and led the opening 32 laps. The No. 27 Heart of Racing Aston Martin was again strong before being forced off track in the last hour; the No. 32 Team Korthoff Mercedes led more laps than any other entry (135) but finished as the last car on the lead lap after being assigned incident responsibility for a late-race clash.

The two key talking points after the race were driver standards and etiquette, and of course, Balance of Performance. More than a few drivers were unhappy with the racing tactics demonstrated by their competitors. Corvette Racing’s Antonio Garcia, a four-time Sebring winner, called it “careless and reckless driving by a lot of guys who should know better.”

“I’d say driving standards for today were pretty sub-par from the whole field,” added teammate Jordan Taylor. “There were so many yellows early on and the end of the race was embarrassing to be part of, to be honest.”

And while the grumbling about BoP wasn’t as intense as it was after Daytona, some competitors still feel there is work to be done to achieve true parity.

“We had so much disappo intment after Daytona, but it was not our fault,” said Patrick Pilet, whose fuel saving down the stretch secured the GTD PRO victory for the Pfaff ‘Plaid Porsche.’ “Then we managed to win this race by being clearly not the fastest, but just because a complete group of people believe in us, believe in hard work and give 100 percent. At the end, for sure it was a gamble, we needed a yellow to be sure to finish.”

“For sure we are closer, but not close enough,” added Risi Competizione’s Daniel Serra, assessing the latest Ferrari. “If you compare with Corvette or Mercedes, they’re flying compared to us. They’re on a different level. But we were in contention for a podium, and I was able to fight with them and see what the difference is.

“IMSA usually do a good job, so let’s see what they do for the next race.”