As a junior road tester I used to love the art of figuring cars. I’d spend half my life up at Millbrook, trying to work out how best to get cars off the line with just the right amount of wheelspin or, more often than not, with no wheelspin at all.

And between myself and my fellow road testers on the other magazines, there was always an unspoken rule about competition – to see who could generate the best numbers, often out of the exact same test cars.

Nowadays, though, with launch control systems fitted to any performance car worth its salt, and paddle-shift gearboxes that deliver perfect upshifts, there isn’t much of an art to figuring a car. You just press a load of buttons in the correct order, bend the floorboards with both feet, then release the brakes and away you go.

And that includes cars like the McLaren P1, whose performance figures seem to have upset one or two commentators because, well, the ones we have recorded aren’t quite as phenomenal as those published by an American magazine.

There are a couple of reasons why this could be so. Perhaps the American magazine figured their P1 with less weight on board than we did – we always figure cars with half a tank of fuel and two people in situ: driver and passenger. Read more about how we figure test cars in Matt Prior's blog here.

Or the P1 we tested wasn’t performing quite as it should on the day, although this scenario isn’t possible really because there were several McLaren technicians present when we figured our car, all of whom were happy things were as they should be.

American magazines have a habit of producing unusually rapid figures on cars, after all; always have done, always will do. Call it the unfair advantage, call it what you will, but for a long time it’s been an unwritten rule of road testing that the US mags tend to record faster times on their cars than everyone else.

Maybe their test gear is calibrated differently to everyone else's, Maybe the average American road tester is forced to eat nothing but lettuce for the three months leading up to a figuring session if the editor knows they are in the chair to extract the numbers from the next big thing. Perhaps time simply passes that little bit more quickly in the land of the free. Or maybe they use 106 octane fuel.