Use 1080i/60 in order to take up to 20 high res stills.
In aperture priority mode mostly you're going to stay at 1/60 and just moving the ISO and aperture around.
You probably want shutter priority or manual mode to go to higher shutter speeds for the race. Fiddle around too much while shooting and you'll notice exposure changes in the video.
If you take all 20 shots it does take a while to dump and be ready to shoot again.
If you shoot video and stills non-stop except to dump the stills the v1 may overheat.