First of all, safety first, do not lay out there in front of a race car. I don't care how precise the driver is, all it takes is a tire go down, part break or some other malfunction and a tragic accident could occur. If you wish to put your camera in jeopardy, that's your choice. If I were attempting that shot, first I would choose a good light day. Second, I would manual focus and set my aperture to whatever depth of field I desired. Remember the shorter the depth of field the less room for focus error. My shutter speed would be dependent on the speed of the cars. The faster the car the faster the shutter speed with a max probably aroung 1/1000 of a second. I shoot Nascar on a mile and a half track at 1/1000. On the short tracks, between 640 and 800. I would burst mode for several laps and take the best of the bunch. Because of safety concerns this is not a shot (from that angle) I would attempt for a pan. Others may have other suggestions, this is just mine.