Didn’t find anything similar so i made this.
The backlights are hard to make look modern, the styles are kind of dated and you can’t really just make a simple modern design for the back.
EDIT: At the same time i’d like to inform about the difficulty to make a brake light, since you can’t make only a single fixture in the middle.
There will most likely be more fixtures added in the upcoming releases.
Although it is very time consuming, You can use the round tail light, make it very small. And try to give it the appearance that it is an L.E.D. …
That might help with the modernization of the tail lights… (but as I said, it is very time consuming)… 
(On one of the cars I had designed, I used a grill on the back of the car - then placed the small round tail-lights inside of the squares, which resulted in giving the appearance of an L.E.D. tail light bar. … 
)
Good word of advice there.
If you are looking to be more creative with fixtures, do please also check out the Car Design Forum. Lots of nice ideas and lots of creativity there!
Making custom groups would be awesome, if you ask me. Would save time, like the vinyl groups in FM4, perhaps?
Already been discussed before and the Devs are looking into ways to save these groups, or being able to change platforms and bodies when willing to change between sedan, hatchback or wagon for example.
This a difficult job to do, though. I would just like to save my fixtures into a custom group, with the correct size, rotation etc. so i can drag and drop them on with the same values. Easier to implement than making bodies changes with the fixtures in place and not glitching.