From the article in the first paragraph: "To comply with today’s stringent crash regulations – by passing offset, side and roof impact tests, as well as those evaluating pedestrian protection performance – cars require considerable cubic metres of controllably crushable bodywork."
If you mean other people not in cars then picking a lighter car wont matter for the people outside. Airbags on the outside of the car are the only real solution.
0.5mv^2 scales too fast for m1 to matter if m1 >> m2.
Safer for the people in the car, not outside it. But I guess that is the point.