Dave is exactly right, newer cars are designed to crumple in an impact. The damage to your daughter's car should be fixable save there being any
structural damage to the chassis. If it's not warped or twisted, it should be repairable. Newer cars have what they call a 'crash zone', which is
basically a tub the driver sits in, while the panels around absorb much of the impact, taking the brunt of the force rather than the driver. Add to
this airbags, moulded seats and generally better brakes than older cars, newer cars are designed more for survivability than older cars.
This is a video on Top Gear Australia, it shows the difference between the braking of a 1970s Ford Falcon (a locally produced 4 door sedan similar in
size to the Mustang), compared to the latest 2012 model. The difference in braking distance is staggering.
My opinion? If the Mustang is fixable, keep it. Otherwise, look for a similar sized modern car with crash/crumple zones, airbags and anti-lock brakes
(standard on most modern cars), and don't worry about the 'plastic' bits.
This pic shows the crumple zones surrounding the 'safety cell' most modern cars have. It does make the car look like a wreck in an accident, but shows
how most modern cars are designed to protect the driver by basically putting the damage outside the safety cell. Hope this enlightens a bit.
A mark 1 VW Golf. Not only are they cool as anything, they are built like tanks. Any problems are also easily solved (mechanically rather than having
to get it rigged up to a diagnostics machine that will forecast a fortune in problems!).
If you get it imported from South Africa (Citi Fox) you may also get run flat tyres and a flame thrower (for when you stop at traffic lights in a
dodgy area).