I recommend downloading the car's map update directly from the vehicle manufacturer's website. Since the car uses different software than the navigation device, the corresponding update must come from the car manufacturer. If the car is able to allow the user to update it, it is most likely with an SDHC memory card.
Hello Susisteine
I bought the Tomtom for my bike in September, but it wasn't delivered until November.
As it's still too cold to ride, to be honest I haven't bothered with it yet.
So I can't give you an answer at the moment, sorry.