Correct me if I'm wrong but I don't think many cars on the market are able to receive over-the-air updates to their systems. I think that's what the parent was talking about specifically.
All of the cars I've driven have been accessible by ODB2 or something similar, which is a physical connection under the hood and/or steering column.
In addition to OnStar already mentioned, some Audi can over wifi/cell. Also the OEMs that use Tegra have this capability though I know of none that have enabled any OTA updates over wifi. Hyundai/Kia had beta hardware that did it over BT a year ago.
All of the cars I've driven have been accessible by ODB2 or something similar, which is a physical connection under the hood and/or steering column.