Julie's car is in the water quite a bit further from the groyne than I'd initially thought. Thanks Meticulously, this picture is interesting. There's a few guys on the beach in suits, probably detectives so they knew it was Julie's car before it came in, that she wasn't in it but suspected foul play.
If an offender wanted to get rid of a car without attracting attention, I'm not sure he'd drive it headlights on along an elevated position for up to 95 metres which is the length of the groyne. Then hope the plan was going to work in that he could successfully bail out of the car before it crashed over a heap of rocks and didn't jag stuck on the side for everybody to see. Or alternatively, stand there like a beacon pushing it over the groyne and hope it didn't get stuck on the side.
So I'm wondering if the suggestion that the car went over the groyne was misinformation, we know the police do it to distinguish genuine information that comes in from false and if they actually know that BLF drove into the surf from the beach.