I think it would be cool if backfires when they spit flames created light around them. So for example in this clip im revving a drag car at night i think it would be neat if the fire was a light source so it lit up the area around it a bit like it would irl.
to make that work properly, you're pretty much looking at implementing global illumination, which would be a massive task to undertake, and would increase system requirements quite a bit (so it would be best paired with a lot of optimisation in other stuff), but it would improve the graphics overall massively.
