id say a ninja hidden in your backseat is the best option available.

since smart car thieves could just tow your car anywhere and if the alarm or whatever is going off they will also disarm it for you if you ask. also whens the last time a tow truck driver has asked to see your registration for a call if not impounded or a police call.......

anyone can call a tow truck and anyone can say they lost their keys and anyone can steal anything if they want too.

kill switch is great, viper and lo jack are even better, removable steering wheel is very popular overseas. my 2 cents.

but if you really care get full coverage insurance with a rental car option as well as gap if needed.