Correct and comment

English as a Second Language English Vocabulary, Grammar and Idioms
1
  1. Lying by the side of the road we saw the wheel of a car.
  2. Lying by the side of the road, we saw the wheel of a car.
  3. We saw the wheel of a car lying by the side of the road.
  4. We saw the wheel of a car, lying by the side of the road.
    Please correct the above sentences and comment.
    Thanks.
2

I think while 1, 2 and 4 could mean the same (we were lying by the side of the road), 3 indicates that the wheel of the car or the car was lying by the side of the road.