With a very basic sound system, the entry level VW Jetta leaves much to be desired. There are 4 6" speakers on the doors but no tweeters, although the rear door does have a hole for it. Overall though, the materials and chassis on these cars are quite nice so it's not a bad daily runabout at all. To address these minor issues, we upgraded our customer's car with the Sony XAV-AX1000 head unit.
This unit offers a USB input for Apple CarPlay which is exactly what our customer was looking for. It has a 20W x 4 RMS amplifier and Sony's DSO feature which really brings the lackluster factory speakers to life. Of course, a pair of 6.5" coaxial speakers would be a huge upgrade in terms of sound quality but that'll be for another day.
It was important for our customer to add a reverse parking camera which is easy to do with the 6.2" touchscreen on the Sony. For this car we used the Axxess XSVI module which provides NAV outputs. This is the preferred way to install a backup camera in a CANBUS car as the reverse trigger has clean power. The other method is to use the reverse bulb wire but this often leads to a very grainy image that is not ideal. We drilled new holes on the rear license plate bracket to lower it about an inch. This lets us use a license plate bracket style camera mount for a centered image while not impeding the trunk release.
If the car had steering controls, the XSVI interface has a plug-and-play harness for the Axxess ASWC-1 so that would be the preferred way to retain steering controls.