“driving to watch the sunrise in Galveston”
“at around 1 a.m. on Interstate 45 in Houston”
It is not that far from Houston to Galveston, and the sun does not rise at 1 a.m. This does not change what happened, but it does not make sense.
I agree that the “watch the sunrise” story sounds bogus.
Possibly the three were at a party and she was their designated driver. Or boyfriend and buddy were out drinking and called her to pick them up.
At 1 a.m. it's likely no one got a look at the license plate so the perpetrator will probably never be caught, unless he brags about it to the wrong person.
There was a similar incident on the Houston freeways a couple of years ago when a black driver got angry at another driver and shot at his car, killing the other driver's wife. I think that was in rush hour, at any rate not in the middle of the night.