If you are looking for an affordable and standard security system, try to consider converting your old smartphone as a concealed GPS tracker. You can do this by simply leaving the old smartphone in your car to monitor its location. Also, make sure that the smartphone has a GPS tracker feature to make this work.
You also need to have a long USB cord to ensure that the phone has sufficient power and will not turn off because it has a low battery level. In case your vehicle is stolen, you can just track your smartphone remotely from any device that has an Internet connection.