I don't have data, but I'm pretty sure you're even safer in a low speed car-to-car accident than in a low speed bike-to-bike accident.
Which is the direction the car size and weight war is going anyway, after all "My family is safer in a massive SUV". Well then. Who cares about everyone else anyway. People outside of vehicles should just stop being poor and get one.
Kinetic energy=0.5mv^2
The two variables are orders of magnitude smaller in one scenario, and the function grows quadratically.
My face doesn't have a few feet of crumple zones on it, just a couple of millimeters of skin over bone.