>What makes you say that?

Two reasons:
1) more steel means the occupant space will remain better intact
2) more steel means your vehicle will deccelerate slower then the light car

Notice when a large SUV collides with an average car. Often the driver of the truck will walk away. This is exaggerated with dump trucks and semis.

>If you're a half decent driver I don't think you should let fear drive your choice of vehicles.

http://www.statisticstop10.com/Causes_of_Death_in_US.html

Car accidents are the number 1 (or two) reasons for death not related to lifestyle. Think about it. We all know someone that has died or been seriously injured in a car accident. Much like we all know someone that has died from cancer.

Death by car accident is under-appreciated by the average person. It is much more realistic to have a fear of being in a car than a fear of flying.