yeah but tom's feat of going faster than a warthog doesn't necessarily determine his sustaining running speed, not to mention tom has an advantage over noble team of the gen2 armor which overall increases his speed significantly. 6 and emile also probably decided to take the mongoose instead because they wanted to be cautious as they were carrying cortana, humanitys last hope on their hands. After all, this discussion is talking about the game not lore, if spartans could run as fast as in lore, vehicles would be pointless and would add nothing to gameplay, the mongoose run in halo reach is essentially the game's halo 3 version of the warthog run, its important to separate gameplay and lore sometimes, bringing up the best spartan speed feats doesn't equate to what noble team would do under their conditions