I seem to remember reading somewhere that the X308 cars had a "kill" switch for the ignition in case the car rolls over and that this switch can sometimes go bad.
Can any one confirm?

 

This is on all vehicles made since around 1987. Its called an inertia switch and it should be behind the right side heel kick.

 

Can it become defective causing a no start situation?

 

I won't say yes, but I will say it can be triggered without an impact. Recently a member was rebuilding his car (disassembled the electronics and reassembled along with his body work) and it wouldn't start, then discovered the inertia switch had triggered.

 

And to add to Highhorse's post: Also seen posts where there had been welding done on the car, upsetting the inertia switch (also some weird electronic issues seem to be related to it)..