If you open it all the way you should be able to see them.
I have a leak in my car roof.
These fixed points can be perpendicular exterior walls a fireplace chimney or other components that extend through the finished ceiling to the attic space or roof surface.
Another pretty big clue will be if your roof is completely rusted over.
Having a leak in the roof of your car can cause damage when it rains will damage your upholstery as well as trickle water into electrical circuits fortunately repairing roof damage is relatively easy and will save a lot of money in getting it repaired professionally especially if your car is out of warranty.
Once you have determined that the leak is caused by a roof related issue measure the location of the leak in the living space from two fixed points.
However if you can see any bubbling or cracks in the paint along the sides that s where your leak is.
If you spot any rust near the roof sand it clean it with rubbing alcohol and maybe even use some touch up paint on top.
They re equipped with drainage tubes that carry excess water from the roof down and then off your vehicle.
If there is a leak and the inside of the car smells like coolant a sickeningly sweet smell when it gets warm the heater core may have sprung a leak.