Why do some ships have better stats shown in orange?

Solution 1:

It appears that the orange bar represents an additional bonus on the base value of those stats. From this thread:

The HD Fury ships have slightly better stats than their HD counterparts. That's what the orange represents. Just an extension of the original stats.

they're not "slightly better," as there are many more stats affecting the physics that are withheld. They are slightly different, however, and the orange marks the area where you'll notice improvements. This doesn't mean the Fury ships are categorically superior, however, as there are other factors that play into their raceability (including shape and size, etc.)

This is also supported in this thread, where users are discussing specific ships, but note the meaning of the orange bar:

Those two just do not have a variant from the Fury expansion (the stat boosts in orange/red).

_{(emphasis mine)}