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THIS TITLE stands for Auto Club de l’Ouest Balance of Performance. The ACO is the sanctioning organization of the Le Mans 24-hour endurance race, taking place as I write this. (At the moment, the race is in its fifth hour, not quite 7 p.m. Central European Time; approaching 10 a.m. in my southern California.)


Balance of Performance is the ACO’s and other sanctioning bodies’ means of leveling the race circuit for production cars of varying capabilities. Generally, the adjustments involve power, weight and fuel capacity. In particular, the ACO has performed more than a bit of balancing directly before the 2016 Le Mans among the five marques in its Le Mans GTE-Pro class, Aston Martin, Chevrolet, Ferrari, Ford and Porsche.

Two of the contenders in LMGTE-Pro. At left, the Chevrolet Corvette C.7R and the Ford GT.

Two of the contenders in LMGTE-Pro. At left, the Chevrolet Corvette C7.R and the Ford GT.

As described at, as recently as yesterday the ACO and the Fédération Internationale de l’Automobile gave LMGTE-Pro entrants their latest BoP adjustments for the race. These are based on performance at previous events as well as testing and qualifying earlier this month at Le Mans. There are perhaps other inscrutable BoP criteria.

It reminds me of the Le Mans Index of Performance 60 years ago; of which more anon.

This year, the Chevrolet Corvette C7.Rs and Porsche 911 RSRs were initially given BoP handicaps based on earlier prowess. Then Ford GTs dominated qualifying with Ferrari 488 GTEs not far behind. Porsches were mid-runners; the Chevrolet Corvettes were at the bottom of the list.

Corvette and Porsche teams complained that the ACO was rigging a Ferrari/Ford shootout as in days of yore. Others said the ‘Vettes were sandbagging in qualifying, figuring that the ACO can make BoP adjustments right up to race time.

The ACO assigned Ford and Ferrari modest weight increases on Friday, extra ballast of 22 and 33 lbs., respectively. It also reduced Ford’s turbo boost at certain revs, worth perhaps a percent or two of output. Conversely, the normally aspirated Aston Martins and ‘Vettes got increases in their intake restrictor sizes, measured in tenths of a millimeter, but still significant.

How well does all this work?

At 1 a.m. Le Mans time, the eight top runners in LMGTE-Pro are Ford, Ferrari, Ford, Aston Martin, Porsche, Ford, Aston Martin and Corvette, all within two laps of each other.

I’d say that’s pretty good leveling of La Sarthe. Though radio commentators raise BoP issues, it’s no more suspect than the old days of the Le Mans Index of Performance. The idea of the ACO IoP was to reward a car of any engine size for exceeding by the highest percentage a predetermined minimum distance for its class.

This Ferrari 166MM, winner of the 1949 Le Mans, also won its Index of Performance award.

This Ferrari 166MM, winner of the 1949 Le Mans, also won that year’s Index of Performance award. Image from

Back in the 1950s, my anglophile motorsports upbringing taught me that the ACO’s IoP was merely a way to make sure a French car, typically of smaller engine displacement, won something. And, indeed, prize money for an Index of Performance victory was comparable to that of the overall winner.

French mini racers like this Monopole often scored well in the ACO's IoP.

French mini racers like this Monopole often scored well in the ACO’s IoP. Unfairly so? Image from

To see whether there was proof of this over the years, I researched Le Mans Index of Performance of the post-World War II period, from 1949 through 1971, the IoP’s last year. There are several gaps; and, for a time, there was another award, the Index of Thermal Efficiency based on an entirely different calculation.



Over the 21 years that the ACO IoP was awarded, 9 1/2 had a French car win, the half being a 0.6-liter Monopole tied with an Aston Martin in 1950. Typically these French minis placed well down among finishers.

This Lotus Eleven took the Index of Performance in 1957. Image from code

This Lotus Eleven took the Index of Performance in 1957. Image from

By contrast, 9 of the 21 wins involved non-Gallic competitors placing within the first five overall. Indeed, four of them were outright winners.

This Ferrari 275P won at Le Mans in 1964 and took the Index of Performance as well.

This Ferrari 275P won at Le Mans in 1964 and took its Index of Performance as well. Image from

Written at 6:00 a.m. Pacific:  During the last half-hour of the race, the ACO showed the Black/Orange flag to the 2nd-place Ferrari in LMGTE-Pro.  The reason: Its side-identification light, used by scorers, was improperly lit (something that other cars had done during the previous 23 hours and 30 minutes).

A travesty of inconsistency. Up until now, my last line of this piece was “I doff mon chapeau to the ACO.” I have deleted it.

At 6:06 a.m., the Ferrari is shown on the official ACO website as having placed 2nd in class. Confusion reigns.

This overshadows the leading Toyota LMP1-H’s heart-breaking failure in the last three minutes of the 24 hours. Talk about drama!

© Dennis Simanaitis,, 2016

5 comments on “ACO BoP

  1. Gene Herbert
    June 19, 2016

    I’m surprised to hear of cars like Ferrari winning the Index of Performance awards. As I recall, it only existed to allow the French to run their little 850 c.c. sedans on the same track as real sports cars.

    • simanaitissays
      June 19, 2016

      Gene, so I recalled with my “anglophile motorsports” upbringing. But facts have a way of refining recollections.

  2. Jim in SoCal
    June 19, 2016

    Speaking as a casual untrained observer, this years BoP adjustments certainly appear to be a blatant attempt to keep Corvette of the podium and have create a Ford / Ferrari finish.

    • kkollwitz
      June 20, 2016

      The Ford GTs pretty much blew past the vettes as they liked.

  3. FW Parker
    July 13, 2016

    The three races with Vettes/FORD prior to LeMans were disasters for FORD….the joke of LeMans and then the next (NASCAR)IMSA race was that the Vettes couldn’t even get near the front…after winning the first three. With a “New”adjustment, and a smart refueling in the last race got FORD into the lead and the Vettes (2nd and 3rd) could not close the gap…but remained 7-10 seconds in arrears for many laps…and still lead the series!

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