Consistency is the key element. control as many of the variables as you can. The more constant you control those things the more consistent the car will be. Things like temps of the working components, oil temps tire temps and pressures. fuel consistency, water temps, tune up etc.
I did some testing on a chassis dyno. we warmed the dyno brgs to a normal testing temps.Then put the race car car on dead cold and started making pulls. It took some 20 pulls before the temps stabilized and the car got consistent. What I had found was that the clearances of the mechanical parts were designed to run at had to be there or it would show less power. Ie, The ring gear and pinion was set up to the temps that it would most commonly see on the racetrack. So when it was colder than that than the clearances were off. The gear oil was to thick as well. on and on. In all it was about 30 hp from dead cold to optimum temperatures. Other details would be things like drag adders. On the dyno I would measure things like Break calipers. If I had a rotor or calipers that was heated more than normal than I would do things like pull the pads back etc. You see once the beaks were applied they might or might not pull away from the Rotor.
Hope this gives you some food for thought. I could go on and on but I think you get the thought process here. Measurements of heat can give you clues as to what is robbing you of power as well.
