That's actually a brilliantly simple idea. Bedbugs die at about 120°. Of course, it is so simple and cheap, the City of Detroit will likely never give it a go.
I came upon this idea long ago. Clients used to ask me how to disinfect their cars after they had transported a dog with a highly infectious disease. I merely stated that in the summer, the interior of the car reaches almost 150-175 degrees which is way past that required of Pasteurization..145 degrees for thirty minutes. Recently, a head louse infestation hit and the recommendations are to bag up contaminated clothes and items and leave them bagged for four weeks. I recommended that they be bagged and put them in a vehicle closed up for five days in this heat. No way a head louse or the nits will live at 150 degrees or longer for several hours.