On the topic of adding Carplay there are 2 ways to go about the task. One is upgrading all the OEM electronics to the tune of $2k plus additional
activation fees n such either through BMW or Bimmertech. The other is the piggyback MMI unit that plugs between the stock electronics of the BMW NBT (2014-2017 i3s) and the screen (irrespective of size). The MMI unit from Bimmertech used to cost more when it came out ,to the tune of $800. Price has since dropped to $650 because of the fierce competition and so many copycats. All the MMI units are borderline the same. There are very small nuances that for the average user would be imperceptible and there are some differences in terms of whether the stock mic is used for voice input, or an aftermarket mic is used. Certain units also require running wiring to the front behind the entertainment screen. Others do not. These MMI units have gotten pretty advanced and now offer both Carplay and Android Auto wirelessly within the same hardware. The most loved one recently is the Road Top that can be purchased from AliExpress (last lowest price $230) or Amazon ($299) . Functionality wise it's the same as the Joy Auto, Andream and a handful of other MMI units with varied strange names, including the Bimmertech one. They're all the same copied hardware from China with slightly tweaked firmware running on it. The choice is yours on where you want to spend your hard earned money. There's a vast spread on price, but the functionality delivered is the same regardless of brand name. They're all slightly glitchy here and there and require reboots from time to time, but it sure as heck makes it a no-brainer to spend $230-250 to get decent functioning Carplay and Android auto, than to spend $650 on the same unit, or to go down the full hardware replacement route and spend $2k. Lots of options for every budget and that's great all around.
Current daily driver: 2017 BMW i3 Rex
Past car history: Nearly a dozen 85-89 Toyota MR2s including 88 Supercharged, 96 Lexus SC300, 05 Tacoma 4x4 manual, 11 Golf TDI, 01 Honda Insight manual