Bear with me...
I came across a channel on YouTube which features a couple of guys who are expert divers.
They're based in the US.
They volunteer to help on missing person cases where it's believed the person may be in a car at the bottom of a body of water.
Apparently the Sheriffs in this kind of case just say that they don't have the resources to check...
So these guys go out on lakes and scan to find the vehicles.
And often there are several(!) cars in one lake. 
They then dive down to check each one and see whether it's the correct car.
If it is then they get it towed out.
They've solved several missing person cases where the car has been towed out and (sadly) has the body of the missing person in it.
I've been really shocked by this and can't imagine this happens in the UK but am wondering if I'm naive?
I would assume that if a missing person is thought to be in a car at the bottom of a lake the UK authorities would check and recover the vehicle and if it were too difficult to recover the vehicle they would at least recover the body?
I also don't think our lakes are full of several cars?
Anyone know?
The channel is this one: https://youtube.com/c/AdventureswithPurpose