For this image, I mounted a tripod on the rear deck, and the car was barely moving, maybe around 5-10 km/h. I was standing behind, just for the case if camera drops. Exposure time of 0.5 seconds, combined with that speed, was enough to create blur effect and thus give this image a sense of speed.

Nikon D750, Nikon 18-35mm @ 18mm, F18, 1/2, ISO 100.