Re car alarms, Nifty makes a good point.... having a car alarm is not worth a Tinker's Cuss if no one is going to respond to it if it goes off (for whatever the reason).
For my self, I dont know if any of the following is effective against a determined thief but at least it gives me peace of mind.
Basically to deter theft, I think "the more ya do the better the outcome" ... so i think using an holistic approach which relies on more than a single device is the way to go.
I am not paranoid about car theft but I try and use common sense with the following:
a) a good quality steering lock($50)... installed with the lock facing towards the floor,
b) an auto transmission gear shift lock (from MID America $US 40),
c) rely on the C4 VATS... Cost is FREE but relies on the battery alone)... however, the incidence of late model Corvette theft dropped after it's introduction,
d) a flashing LED on the dash $8 ... ie to simulate a car alarm :-),
e) in public, I always park in open places with lots of people around and at the least someone may be able to give a good ID of the thief who took your car PLUS thieves usually try to avoid working in well light areas with audiences,
f) at home, I use a lock up garage,
g) use a motion-detection patio lights on access ways from the street ($80 from Bunnnings), and
h) for when a thief eventually takes my car, a good paid-up agreed value Insurance Policy... ensuring that I have adhered to all the fine-print conditions.
In summary, I use a combination of devices to deter theft.
OH, and also, I have a couple of Rottweillers.... :-)
