Mohtaram @VCheng Sahib,
Immobiliser is a deterrent against car theft in case you park you car and walk away for a while. A Corolla parked for sometime can be stolen by an experienced car thief in about 3 minutes. If Indus Motors equips its Corolla with an immobiliser, it can't be stolen. The stories I've narrated are about parked Corollas and do not involve car-jacking. If someone puts a gun at one's head at a traffic light, he or she can still score a legitimate kill if he or she is properly trained in car-defence. Every situation has an answer. I'm particularly addressing the situation of a parked Corolla which is so vulnerable to theft that Indus Motors has to do something about it. I can say that Indus Motors is oblivious to the situation to a shameful level and turning a blind eye towards a situation which has to fixed.
Here is what happens if one tries to mug a trained guy sitting in a car. Read this and appreciate for yourself what Justin, a former US Special Forces soldier did to his mugger. Justin forced his mugger to shoot himself in the ankle. One should get trained for such situations. Justin is a former US Special Forces soldier, a martial arts champion, trained in hostage rescue and much much more. Here is the link to the story: Chicago Martial Arts Champion Forces Mugger to Shoot Himself
Remember the best self-defence weapon is the human body, then comes 9mm which is not the caliber for self-defence. My favourite is 45 ACP which is bigger and has more stopping power than 9mm and is less likely to kill (as compared to 9mm). One is less likely to be charged with murder if he ends up using 45 ACP because it disables the bad guy than killing him, the likelihood of which (killing in self-defence) is more if one uses 9mm.