I think you should be able to see the car in the mirror (or have an option to do so) for a bit more realism (which is the main point of the game) and for me would be a nice addition to the overall impressive game.
The mirror issue is one that the community is asking to be fixed, and is quite easy to fix. The devs just haven't gotten to it
That's a... weirdly accusatory way to phrase that. The current reflections system works by collecting a real-time cubemap from the center of the car and projecting the reflection onto the body panels, mirrors, windows, etc. Its main advantage is that it can provide adequate, functional, and fairly inexpensive reflections (that can also double as global illumination for the player's car). The disadvantage is that because there is only one source point for the whole vehicle, the vehicle itself cannot be represented in the reflection, otherwise you'd have anomalies, such as the vehicle's interior being reflected on its exterior. There is a new viewport system that the community has uncovered in the code, which allows each of the mirrors to have its own unique perspective and to accurately reflect the car from that point. A few recent-ish posts from the Update Speculation Thread have more information on and even video of this new system in action. However, it's pretty glitchy and probably not very performant, so you may have to wait until the system is officially added into a future update to play around with it.
So it is possible to have it work it would take some performance and not work 100% reliable is that correct?
In the current version, yes. The feature is evidently a work-in-progress, and so isn't integrated properly into the game right now. There's every chance that the viewport system will eventually be stable and performance-friendly enough that it will be officially released and accessible through the game's normal graphics settings within the next few updates. Though I do caution you not to take that as a guarantee. If you want to play with the viewport mirror system you'll need to find someone who has made it work and ask how they did so. There's more info (and a video) here: https://www.beamng.com/threads/update-speculation-thread.20246/page-2886#post-1615621
So it is just a hope for it to be added and wait because as far as I saw there are some major issues when you enable it causing "shadow flickering" or going back to alpha graphics potentially without shadows.
