Honestly, the type of plane makes a big difference. A cessna 152 has a stall speed of about 40-50mph depending on load, with full flaps and no power. Landing speed is recommended at approx 70-75mph. It's likely, if he landed with the flow of traffic, that he was able to glide in at about the same speed as the traffic and put it down in a gap of cars.
This is exactly why you practice controlling power off speed and descent rate, as well as power off approaches/landings.