The subframe mount areas are prone to going on these cars. Dirt and grime collect in the little pockets, water seeps in, and that's all you need to get started falling apart.

These repairs aren't bad, but they do take time. In a corner area like this, you have to deal with multiple planes converging at one point. So cutting in, it's best to go slow and be sure you're only cutting one layer at a time. Doing that will help you in building your patch pieces.

I like to try to replicate these areas as close as I can, even if it is out of sight and can't be seen. Like good nachos, this patch is multi-layered and extends deeper than the surface. It's pretty critical too, since the subframe unloads its stresses into adjacent metal. Stiffen the area around it, and you stiffen the area, itself.