In the software that came with the printer it has an "Auto Support" feature that figures the best way to add supports while printing, but sometimes you need to add, remove or relocate some for the best print. I've also found that sometimes a part you find to print may have been drawn at full scale size, and when you shrink it to 1/25th scale the wall thickness is too thin to print out. Most of the resin printers also don't have a large enough print area to be able to print a full car body at 1/25th scale.
I have heard of a few other manufacturers offering resin 3D printers at good prices, but have only seen pictures of parts printed with them. I have heard that Anycubic is suppose to be coming out with a resin printer with a larger print area, so it may be possible to do a full body soon.
The biggest thing with any 3D printer is either being able to draw what you need to print, or be able to find the file, or pay someone to draw it up for you.