I couldn't find any existing threads on this, so figured I'd post what I found here in case it helps anyone else. I tried to connect to the xfinitywifi access points a few times, but the car failed each time. I figured it was probably that the car didn't have the logic to handle the captive portal, so there was no way to log in and register the car with my account. I noticed that by tapping on wifi settings there was a little (i) icon which showed the mac address. So I made a note of it, and grabbed my laptop. On Linux and Mac you can change the local mac address temporarily using the ifconfig command as root - I've no idea about windows, but maybe someone else can chime in. I changed the interface mac address to be the same as the car (ifconfig en0 ether 90:03:b7:aa:bb:cc) and then clicked on the xfinitywifi access point, logged in and named the device. Then disconnected and changed my laptop's mac address back. After doing that, the car was able to connect successfully as the mac was now registered.