... if you watch the crash test TopGear showed in its last episode. The setup was taking a truck, driving a traditional hatchback or a sportscar against it and see the difference.
And if you take a really flat car and tweek the height of the truck a bit you can proof anything of course.
But, of course, this is not to be taken seriously. Safety of classic cars is primarily dependent on the driver, as the car will not offer a lot of passive and active safety features. If you are aware of this, then all is fine. So drive carefully, look ahead and plan for safety tolerances.