Storing fuel in the long term is complicated, mostly because gasoline or diesel fuel are not meant to be kept as they are in a tank, but need substances to keep their compounds stable in time. In racing cars that use methanol, for example, they will need to be sure that the fuel has not gotten too much water vapor from the atmosphere, as that will cause other issues later.
In the video below, you can see the two-time Pikes Peak winning Toyota Tacoma hit the dyno, as well as listen to what Rod Millen has to say about his purpose-built racecar that still has its signature Pennzoil livery.
Since Pikes Peak only has its racing course open on race day, racers always have to be sure that everything is perfect in their cars before attempting to go against the clock up the mountain.
A big challenge that tuners face when preparing an engine for Pikes Peak is the difference in altitude that they encounter, which can make some of the sensors on the vehicle deliver erroneous results.
For example, a vehicle can drive fine and perform at its peak on the dyno in a workshop, but might struggle with fueling as it goes up the hill at Pikes Peak because of the difference in air pressure.
Seasoned competitors already know how to tackle this, but those who do not take that into account will have to make last-minute adjustments to their ECUs.