I currently drive a company vehicle and pay tax on the privilege but work want to put trackers in, these trackers are used for every stop / start and where you have been. Can they force these to be put in?
While you pay the tax for the privilage of having a company car the car itself is being paid for by the company, so as kawakiri says, they can do what they want.
* ask the company to give you the means to disable the tracker outside of working hours
* tell the company that you no longer want to use the vehicle for private use and require them to provide a 'base' where you can leave the vehicle outside working hours.
In this case you would then have no tax charge for private use (but note that the taxman includes commuting as 'private' so you would need to demonstrate that you were not using the vehicle for that purpose) - simply leaving the car at your home and not using it for private mileage is hard to prove and probably won't satisfy the taxman.
My employers ditched all company cars in 2004. We now get £300 per month car allowance and a fuel card and just log personal mileage for b-i-k taxation. They hope the £300 per month allowance (which is taxable) will persuade us to buy nice cars that convey a good image to customers, rather than using the allowance to buy cocaine and wobble round in a 1988 Carina.
The short answer to the question actually asked is "yes", they can. It's their car, they can do what they like with it. No-one forces you to use a company car, certainly not outside working duties anyway and inside working duties they are perfectly entitled to know where you have been with it.
There would be no point in having a tracker sunny-dave if there was a way to disable it.
Yes, as you have been told the company own the car and they can do whatever they like with it.