Wired spoke to Iain Litchfield, owner of Litchfield Motors, a popular tuning shop in the UK. Litchfield says that making non-factory software changes to cars (outside of tuning, of course) has been popular for a while now. For example, someone in your area may be able to add “comfort access” to your BMW, making your windows roll down when you hold the “unlock” button on the keyfob. Similar practices are popular on VW and Audi cars as well.
People who will help you shed the software-as-a-service (SAAS) model do exist. You just have to find them. Litchfield, for example, has. “On our 2014 BMW M4 we hadn’t specified the TV option, but we were able to turn this on in the software. You can even set it to turn on the TV with the car in motion, which is illegal. We changed the DAB radio setup, central locking sequence, even the length of time the automatic wipers run for.” These people will, of course, help you unlock the heated seats that are already in your car.