I agree with the op in that it is counterintuitive for the tiny searcher ship to be slower than the medium-hulled surveyor and the cargo hulled colony ship.
It feels wrong. Not arguing realism. Fully understand that larger ships would have vastly more speed in space than smaller ones from any conventional physics standpoint.
Too much realism can quickly kill a good game, too little kills immersion. In my opinion Gal Civ 3 has erred on the side of too little.
Back to the Op:
The scout has no drives, the colony ship does. It does get a speed boost by virtue of being tiny, +2 I think?
I don't think so.
It has a base move of 2 modified by +1 due to your race's "Fast" trait.
If you create a race with "Dense" your tiny hull should have enough capacity (30) to have an engine on the default template. I don't know if it will, I've never tried it and I do not know how the module priorities in the .xml for that core design are layered. I do know that it's viewable and that a modder, I am not, could post it here with ease.
Solution: Mod the starting scout ship to be the small-hulled scout instead of the tiny one- or petition the devs to make that change to the game. The mod would have to be entered separately for each race ,I believe.
There's another option that would fix your immersion quandary suggested here: https://forums.galciv3.com/474028/page/2/#3615447 (modifying the base stats of ships based on hull size and ship role, like ManiNames "thinks?"
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