I like making custom slot car bodies but I truly suck at painting windows. So for bodies that I customize often, I make water slide window decals. 

This is a set of laser printed water slide decals on clear decal film for the AFX Audi R18 body. Several people make resin or 3D printed LMP bodies similar to the R18 and these might work. I have only used them on the AFX Audi R18 body. 

You get four full sets (enough for 4 bodies). The second photo shows the current print style I will use to fill orders, which includes the headlights.

For each decal set, there is one windshield decal (that goes on as a single decal), head light decals, and 2 sets of side windows (1 set full height (that set pretty much matches the lines on the body) and 1 set that is shorter). I decided I like the full height version and that is what I use, but my decal template include the lower height version also so I am offering it.