It will make some difference but will not stop all attacks.
Putting in a real camera will not be any better than a dummy because, if they're going to do your car they will and they are not totally stupid and will wear hoods, just like the old highwaymen and cowboys wore masks so they could not be positively identified.
One of our local papers often prints pictures of villains who have stolen things or held up shops. I am always amazed at the poor quality of the pictures and even those without masks could be just about anyone, so bad are the photos.
Your system will be very unlikely to identify anyone enough to prosecute or even apprehend.
Putting in a real camera will stop 99% of attacks as firstly it serves as a deterrent, the infra reds on most modern cameras now are very bright and make the camera very visible at night aswell..Also once the cameras have been in place a short time, knowns work this out and stay clear, you would be surprised just how quick word of mouth travels amongst the louts of this world, FB, Twatter etc etc
Your local papers are printing pictures of villains from very old in the most part antiquated equipment normally still using old VHS videotape machines, most of the time what you see on the tv and in papers are freeze frames from shop videotape CCTV systems, that have been in use for many years and are well past there sell by date, the videotape itself has been recorded over many hundreds of times and this degrades the tape over time and the result is no legible picture or footage when they need to review it..
Most systems sold nowadays are HDD based and suffer no such degradation problems, they also have decent quality cams now as standard, these systems are only just starting to filter through to your average shopkeeper though as prices are now dropping due to better tech becoming available at cost.
The cameras TXD have linked to on ebay are 700TVL cameras which are pro quality and will be able to pick a face out and be clear as a bell from 50 metres..
As a side note
I had the police here just 2 days ago asking me for footage from my cams over a theft that happened across the street from me 40 yards away, I checked my HDD recorder found the footage and the police are now in the process of nicking the culprit, first thing the copper said was how nice and clear the footage was and wished a lot of the shopkeepers he deals with had equipment like mine, and that he knew the guy involved and was a known to the police!
Job done..
So CCTV does work if you have the right equipment!