Thank you, I'm feeling a bit better today so I've been able to think about it and things don't add up. We live on a farm track and my cat never went down to the road in the 7 years I had her. Where I found her wasn't on the side of the main road but up the track slightly so whoever put her there knew where she lived. She always went up the track towards the farm at the end (the other direction from the road) and the people who live there always drive 60+ mph past our house (and have the cheek to have a slow sign by their house) so I am now thinking she went that way, they hit her and then took her down to the road to make it look like she was killed there but they made sure to place her somewhere I would definitely see which was obviously away from the main road. I am almost certain my cat would have been killed instantly having seen her so I don't even thing she would have put herself there.