We've all heard the old saw, "The bigger they are, the harder they fall."
Well, the same is true of cars.  Heavy cars have that much more inertia to
crash with.  Drop a nerf ball from a 10 story and it lands undamaged; drop
that Heavy Chevy or Dodge Ram Tough and you wind up with a ball of metal.

The secret to 60 miles per gallon coupled with excellent performance we're
used to is lightness.  A criticism of the all-aluminum car has been it is
1. Expensive and 2. Irrepairable after an accident.

1.  Too expensive.  Yes, if hand built as are all aircraft.  But aluminum
can be adapted to the mass production assembly line and will cost little if
any more than a steel lead sled.

2.  Collision repair.  Build the car in three bolt-together sections: front
end, passenger compartment, and rear end.  In a collision, replace the 1/3
damaged.  If a car is hit hard enough to telegraph the damage, then it
should be written off, just as a steel car should.  There are too many cars
out there that have substandard collision repair....there is only a 1/4
inch tolerance from true size on frames and this is seldom if ever achieved
in the old fashioned body shops we depend on.  As for "frame straightening"
by applying hydraulic jacks to force steel back to its original shape, this
is dangerous and should be outlawed.  In the future, when you buy a used
(pre-owned) car, you will be assured of not being stuck with somebody's
wreck.