ugh I should have known you were using a tripod lol.. forgot about the whole chopped bonnet/engine hahah. There is a bit of blur in the pictures which is what made me think about it.. using a shutter release cable or just pressing the button to snap the photo? If your just pressing the button thats probably what it was from.
Yeah I always forget to check some of the basic things like which way the wheels are facing, what shaddows are on the car, whats poking up behind the car etc etc untill I get home and notice on the pc.. I find myself scanning all over the viewfinder when taking a photo more and more now though, it starts to become second nature.
Just keep trying and practicing thats what its all about