They tried to recreate "Speed" with a different vehicle.
It just doesn't work, "Speed" is corny enough, "Unstoppable" is similar, but with less emotion.
Out of the two i'd rather watch "Unstoppable" (this is my personal opinion).
There's only so many high speeding vehicle movies that they can do, if they do anymore they will start to look like that corny Judge Reinhold TV Movie "Runaway Car".