When I'm driving and need to slow down rather than going straight from accelerator to brake I often just ease of the accelerator. Especially when I'm going from a 40 to a 30.
This seems to annoy some drivers, seeing a small gap in front. Someone today must of sped massively to overtake me. And started to brake sharpy he moment they overtook me. It was quite dangerous. I was doing about 42mph and letting the car slow a bit naturally in a 50mph zone. All that happened is the Car in front got to the traffic lights that were red a few seconds earlier.