Interesting basic walk through of Kia Connect with obligatory comments about the slowness of the app.
Whether the car information is being sent straight to the phone app, or (more likely) through an intermediate cloud-based server, either way the car has to have an internet connection. This will be a GSM/Phone SIM and the connection speed from the car will vary enormously depending on which network the car is connecting on and how far away the nearest cell transmitter is. My guess is that having your car in the garage while you run the tests isn't going to help! It's probably only getting a GPRS or Edge rated connection.That is awfully slow :-(
Volvo v60 phev from 2012 did not have these issues, it worked like a charm. Hope it is more a server capacity issue that the need to extend..