> I guess like you say, working out whether a component will snap under a 
> given load is much easier than determining (say) whether a car engine will 
> explode when you ignite petrol vapour inside it.

Yes, in fact some calculations you can even do by hand without simulation 
just by using elementary beam bending mechanics.

> Even so, I'm kinda surprised at the lead-time for a prototype. Mind you, I 
> guess if you just want to build a model of something, that's quite easy. 
> If you want to build it out of the real materials for strength test 
> purposes, that's a tad slower...

I did have a break down of the lead time somewhere, but there are mechanical 
parts, optical parts, electrical parts, which all have to be designed in 
complete detail and work together (your electrical engineer can't say he 
needs a PCB that is bigger than the mechanical housing, and his circuit 
needs to give the correct voltages to the LCD etc etc), then the tool-maker 
must take those designs and design and build his tools, then the tools have 
to be approved and tested to make sure they are making parts with the 
correct accuracy, then finally the individual parts can be made (perhaps 500 
pieces for a typical prototype run), and then they are assembled.  For the 
later prototype stages they have to actually be made using the same 
equipment that will be used for mass production, so the whole assembly line 
needs to be set up and checked etc.

> "And in this test, we're going to crash a new car into an 20-year old". 
> Uh, and where did you get that from, exactly?

I think the crash test standards give quite detailed information about what 
you have to crash into.  All those crash test dummies you see are made to 
exact specifications that simulate eg the 95th percentile of human 
proportions and weights.

> Also, why do they already have to be painted random colours?

I don't think the colour matters too much, but they usually have all those 
circular stickers on them divided into 4 for the software to easily measure 
the movement and distortion of the car from the video sequence.

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