Back to bugs, my truck is covered in them. Having been sat it the sun, they are well and truely baked on. Last night my Mrs decided to use the windscreen washers, which didn't end well. As one keen to try whatever product I have in my armory for something other than was intended, I sprayed on some 1:10 diluted Pro-Green cycle wash. left it a couple of minutes, then used the windscreen washers to wash it off. Brilliant. Virtually every bug and smear gone in no time with no scrubbing.
Best to keep it off the paintwork though, as it will strip your wax straight off. Having said that, as one of the first stages of a deep clean, that would be a good thing.