More likely the dog will just bring the thief its toys and get the iron bar in return.
Make sure your dog doesn't have a collar on while at home. That iron bar would be more effective under the collar and twisted to choke it than trying to hit it.
How comes car manufacturers don't add in remote immobilise feature into cars these days.
£300 phones have them these days. It's not exactly expensive.
You'd think so but it's in the name of safety. They don't want cars konking out in the middle of the road, motorway or junction. Easy way to get around this is to immobilise it once it comes to a stop.
They could tie it to another object that you'll always have with you, if the distance becomes to great the system is triggered. But then they'd just steal that object too, if they knew about it. It's too dangerous to make an anti-theft system that relies on a body part to start it, for example iris, face or finger print recognition. Imagine what they'd do to you then!
So you can't stop them from taking your car but you can deter them; if the likelihood of being caught is high and the consequences severe they won't take the risk. Imagine a system comprising of a few hidden cameras inside with good lighting (including IR) with a mobile phone data connection that broadcasts live via facebook or remote server. Car thieves rarely drive around with balaclavas/masks on so they will be easily identified. Plus a brightly lit car interior will stick out during the night!