Hi there.. There are actually 2 bottle necks here..
One is the browser that is damn damn slow, and another one is Proxy servers that are used by tesla.. For exmpl, i live in Vienna (Austria).. When i connect over my WiFi i am getting speed of up to 5 - 8 Mbit/s on and of course i see my Austrian IP.. When i connect to the Internet over SIM in car, i am measuring max of 2,5 Mbit/s and i am connected over KPN IP (Netherlands).. So, it is cool that LTE connection has been established between the car and mobile operator here (T-Mobile in Austria) but as for surfing speeds you can forget it!
That brings me to the question.. Is it possible to to make some kind of request and change the SIM card in the car with your own or simply use an AP in car and then gain full access to Internet (Youtube and other video sharing sites)..
Thank you..