What is the G load on the passengers?
The body cant take more than a few G's constant before people will up and die.
They can take sustained G's for only a very very short period of time.
A top fuel dragster goes from 0 to 100mph in .86 seconds giving you a G load of around 5.4 g.
Human tolerances depend on the magnitude of the g-force, the length of time it is applied, the direction it acts, the location of application, and the posture of the body.
A hard slap on the face may briefly impose hundreds of g locally but not produce any real damage; a constant 16g for a minute, however, may be deadly.