I have experience tracking Lojack equipped vehicles from a car with a receiver and a helo with a receiver. The main problem with the vehicle receiver is the fact that you have to be relatively close to get the signal. Once you have the signal it is not difficult to track and locate the transmitting vehicle. The helo has a much greater range than a vehicle equipped receiver. It is also very easy to track down a car from the helo. I have also got experience tracking a vehicle with a cell transmitter giving GPS info. The only problem that I have encountered with a GPS system is lag time. I don't know for a fact that it is true, but the dispatcher advised that the "Onstar" people told her that the location is only updated every thirty seconds. Add that to the time that it takes for the GPS dispatcher to tell the Police dispatcher/call taker and then get it forwarded to the actual dispatcher who puts it out over the air to the street units and it adds up to a lot of ground between where the car was when the coordinates were given and where it actually is at that second. It is pretty frustrating being one step behind the car (this should be less of a problem in a rural area, but makes it hard in an urban area).
The GPS system is much better (IMHO) for the vehicle owner; the car is disabled, the badguy(s) get out, and the police recover the car intact. The Lojack type systems are better for the police in that they have a very good chance of getting behind the car with the badguy(s) still inside. The downside for the owner is the likelihood that if the police don't immediately box in the car there is inevitably a vehicle pursuit and the likelihood of recovering the vehicle with no damage once that starts is slim. But for the police there is a high probability of capturing the badguy(s).
Sorry for the rambling, just some thoughts from seeing both types in action. There most likely are many other systems out there that I have no experience with, and if there is a gps system out there that eliminates the middle man (calling to dispatch, having to pass on the info through another to the Officers on the street) that would be the bomb :8

I heard a rumour that the tracker/lojack system may be dumped for the GPS/phone system - not confirmed.

Tracker/Lojack and helicopters make a great combination. As Helopolt1 says thay allow police to catch the thief. Not immediately of value to the specific car owner, but of course, if the thief is in choky he cannot be stealing cars.

GPS seems to me to be good (except it tends to take helos out of the loop). Hp1 has highlighted one problem with GPS: the lag in information getting to the troops on the ground/in the air. The other disadvantage seems to me to be the ease with which GPS information can be blocked. This means that the professional thief, for whom this is a business, can hide a car and move it around, if he can be bothered to get organised. It is probably better not to be too explicit in case someone on the site is not who they say they are.

Logically, the best system combines the two - they do exist but are more expensive (of course)!!

I've got a Vehicle Tracking system from http://www.directions.ltd.uk, installed in the car with a sim card, can send me a text message if my car moves after setting it.

Can call it from my pc at any time, and get the location, and location history.

A very good system which works well.

Hi danfulton
Your link does not seem to work...is the website address correct?
Cheers
WLM

Try missing out the comma :

http://www.directions.ltd.uk