Women always fear a small car as being un-safe... then boast about SUV's... not realizing a unibody construction is better than a frame on structure during impact.
Aluminum serves a good purpose of being light weight, but is also a lot more ductile than steel, and generally can crush more than steel, keeping the ride down curves flatter.
basically take a can of coke, as you crush it it is absorbing energy, when it cannot crush anymore the energy required increases, and the force is transferred through with minimal loses. So with steel, you have a higher "pre-crush" coefficient meaning an increase in g levels to begin deformation of material, then you go into a ride down of absorption, and immediately spike as it becomes harder and harder to crush the material.
With aluminum your ride down curves are substantially flatter, and your peak force is much less as well. this is all less energy transferred to the people inside the car.
Uni body construction provide a more solid cabin space to the occupants, allowing energy to be transferred around the cabin and not through it.
also your momentum is much lower with the cars weight, meaning your shock durations are over quicker, which means less energy is allowed to propagate.
and etc... etc... etc....
as a general rule... you want a car to have a very rigid cabin structure, but very ductile support around it... you want the car to crush, so all the energy is lost there and not through the cabin.
and then there is a bunch of things on driver seating position. axially you want energy to go through your legs as much as possible, as you knees act like shock absorbers... on SUV's you sit more upright, and the majority of the force is absorbed by your rib cage.
you also have a lower center of gravity, and your roll center is much lower, meaning during an accident, rotational motion is decreased... last thing you want to do is crash and have force acting on your brain perpendicular to line of sight... brains don't do to well in these conditions.
if all else fails... get a mistress.
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Where are my aluminum pedals? 
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