Character mistake: Previous episodes have established this story arc to be occurring in the year 2154. Yet here, when T'Pol records her log, she cites the date as 2152. (00:32:00)
Character mistake: In Engineering, Trip calls Commander Kelby "Lieutenant."
Answer: Warp factor has always been inconsistent and hard to pinpoint, or there's too many episodes that contradict the conversion rates. Changes were made in converting warp factor into actual speed between TOS and TNG. It seems ENT reverted back to using TOS method, which is "warp factor cubed" equals how many times the speed of light they traveled. So warp 4.5 means 91.125 times the speed of light (c). Although in "Broken Bow", with the travels from Earth to Neptune and back in about six minutes means warp 4.5 is about 86*c. However, in "The Expanse" episode, warp 5 was 200*c (instead of 125). 1 ly at 91.125*c is about 4 days, but 100 ly would be 400 days.
Bishop73