It never ceases to amaze me that most people equate size to safety. It's just not true.
I will give one example. Two vehicles are involved in an accident where they are hit broadside by a large truck.
One vehicle is a SRT/10 pickup. The other is the Fiat 500. Which is safer and why?
The pickup has more mass, and has 4 large sticky tires on the ground. More of the energy of the collision will be expended on the pickup and it's passengers before it starts to slide sideways after the tires finally lose their grip.
The Fiat 500 has less mass, and smaller tires. When hit it will start to slide sideways sooner, therefore transmitting less of the impact energy to the passengers.
In the case of a head on collision, there are other factors also. A body on frame construction like the pickups will generally transmit more energy to the passengers, than a unibody constructed vehicle like the Fiat 500. The reason for this is it's easier to design in crumple zones in a unibody vehicle than in a body on frame vehicle.
And does anyone want to guess what a pickup would look like sandwiched between those two trucks. It would probably be just a larger ball of steel, but the results would be pretty much the same.