A good all-purpose cleaner made for automotive cleaning is what I use (Auto Solutions M-50 all purpose cleaner). I liberally spay/soak the front in it and get back to cleaning the inside... it dries, so everytime I need to walk arund the front of the car, I spray it down fully again. It may take me 1-2hrs to get the inside cleaned to a point that I feel it's time to start the outside; I've already presoaked the fascia a number of times, so I only lightly spary the front with water and soak the rest of the car. The little bit of water used on the front reconstitutes the M-50 and then I can just brush most of the bugs off while I do the whole car.
The regular brushing while washing the outside cleans the majority of the bugs off. I go back with a bug sponge and car wash soap/M-50 to get the hard-to-remove stuff and; voila!