One other thing - 2.4hrs does seem a bit short. Maybe we could do 2.4hrs with a 2wd car, then 2.4hrs with a 4wd car, track in the opposite direction? Then you have done 2 & 4 to keep up the 24 theme
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However, I appreciate that my suggestions are placing great onus on individuals letting their equipment be pounded around the track for prolonged periods but just ideas.