[Russ]

The majority of car thefts are opportunists such as Johnny Criminal has just been let out on bail from a police station 10 miles away and needs to get home, or the local chavs fancying a spin somewhere so on that sort of basis factor 2 is an excellent deterrent (although some employ a "what we can't steal we'll burn" attitude) but as you say if they really want your car they'll take it. A police officer recently told me a good way to think of it is which choose which methods will create the most noise, take the most time and draw the most attention to the car. He also said when leaving it in a carpark a lot of people thin to tuck it away in a corner or hide it amongst other cars as if to 'blend in' but all that does is give the thieves cover. Leaving it exposed will means any attemps could be seen by anyone.