What are the websites or applications that common GPS tracking devices use to display location data?

I am being tracked by an abusive family member. I need someone's help. I am 90% sure it is on my car, a 2000 Grand Am. A phone may be more likely, but I have gotten a new phone and new number and I am 100% sure it is not the phone. My location is in the Midwest, USA.

I've tried looking for the GPS unit in my car. I have been tracked for at least 5 years, so the unit must be plugged into a power source. I've checked under the hood and behind the center console panel, and I haven't found it. (I assume the unit has to be in one of those two locations, because the trunk, for example, has no power, right?) Then again, I could be missing it since I don't know what I'm doing. The car has no built in navigation system.

But I have access to this person's email account, web history, and only computer. So before I tear apart the car looking for the unit, or pay someone to do so, I want to be 100% sure the tracker is in the car by finding any evidence of the tracker on the person's computer, which is a Windows laptop (Dell). This person is not tech savvy at all, and there's no way this person knows about clearing browser history, Incognito, password protecting the user account, etc, even basic stuff like that.

What are the standard websites or programs that most units use to track someone? Like the most popular brand names of a consumer level GPS device. The person does not have a smartphone or tablet, so I assume that the person has to be receiving the location data on the computer, correct? Is the location data usually sent through a website, email alerts, or through a dedicated program?

Edit:

Some are skeptical that my car is being tracked. Here is some more info.

• The person is not following my car. The person has known of my location, called me to let me know that my location is known, and all while being many miles away from my location.

• It is unlikely that someone or several people see me in person and report my location to the person. Even when I drive to a location I have never been to before, and I am alone, and I have told no one where I am going, and no one at the location knows me, the person still knows the location.

• When I am in a friend's car, or not using my car, the person has never commented on my location. Not one comment if I am without my car.

• The person has informed me of my location when I had no electronic device on me except my phone and I told no one of my location and I went to the location alone. I had originally thought it was my phone several years ago, but after getting a new phone, new carrier, and new number, and the person still knowing my location, I know it's not the phone.

• The person knows my location fairly immediately, so it would have to be something that is providing updates in real time.

• When I have asked the person if there is a tracker in my car, the person becomes aggressive and does not answer the question. If the person wasn't tracking me, the normal reply would be to say something along the lines of, "What are you talking about?"

• There is no way that the person has the ability to install a tracker on their own. They would've paid someone else to do so. And at the time I suspect it was installed, at least 5 years ago, the person had a key to my car and could've easily driven the car to a technician who could install a tracker.

• The tracking is not via Google Location History because I don't use Google for email, my email password is regularly changed and extremely complicated, and my email provider does not have an advanced location tracker like Google does.

• Even if the person did have access to my accounts, the person has known my location even when I didn't log in to an account in that location. The person also has known my location before I had a phone that could access the web.

• I have access to the person's cell phone. The person does not use SMS at all and has a very old phone w/o internet.

• On the person's cell phone bill and on the person's landline phone bill (one is Verizon, the other AT&T), there is no mention of a second line or device.

• I have never logged in to any of the person's accounts from any of the locations that the person told me that I'd been at.

• I am not on any social media sites.

• To my knowledge, and unless it is concealed, my car does not and has never had OnStar.

I still haven't received any answers for the question in the title, so if someone has been on the other end of a GPS tracker, please let me know how you got the data, thanks.